My last FMT, also in a small party, used it, but he was specialized in 2Hsword and Staves and had 1 pip in 2Hweapon, he gave up dual welding for the use of Lilacor (an early game +3 weapon with really useful protections) and Carsomyr (50% MR and dispel on hit), and the staves, Ryn +4 and then Ram with that +10 dmg super useful as gets multiplied in the stab.
It can be used by both of them if MR is needed and also for the 3 Dispel Magic charges, DM at lev 15, so not so effective vs the late game bosses, while the DM on hit is at lev 30, but all your party can use the SotM that also has DM at lev 30 on hit + very useful protections.
Carsomyr deals 1d12+5 (slashing), +5 extra vs. chaotic evil and gives -5 Thac0, SotM deals 1d6 +1 (crushing) and gives only -1 Thac0 even if both are +5 for the enemies they can hit, Ram +4 deals 1d6 +10 (crushing), when upgraded becomes +6 dealing 1d6 +12 (crushing)+1d4 extra (piercing) and has 10% chance (15% the +6 one) to knock back the enemy and stun him, something that some players hate, but I find pretty useful in a small party as sends away temporarily an enemy when many are around or buy you some time to do free ranged damage when you are facing a single enemy.
As Crushing is better then slashing, less resisted, and Ram is a more reliable and effective way to deal damage my FMT was using it as main damaging weapon, switching to Carsomyr only when dispel on hit or MR was needed, but still Carsomyr can be really useful i.e. you don't want your enemy thrown away when you are using GWW and with GWW and the dispel on hit and damage of the holy sword a FMT can carve trough a WK dragon in a round taking down his protections with the first hit and his hp with 6.5(on average)+5+STR bonus+5(if he is CE) attacks, he will fall before he can react, battle won without using a single spell, I have done it.
So if your FMT has pips to spend in 2Hsword to use it is not a bad idea at all, but you can live without it as the SotM covers the dispel on hit and Ram is just as good, if not better, to deal damage.
Haer Dalis will better use weapons that allow DW, better +1 apr weapons or weapons that have other powerful effects like Blackrazor, I really don't see him using Carsomyr as main weapon as he will lack of APR with it. He can still equip it if MR is needed to survive, equipping it and then the ring of Gaxx and singing he gets 70%MR, but as he can use spell immunity it is very situational. He can also use it to dispel on hit with better thac0 then with the SotM.
If your FMT will spend pips in 2Hsword there is an other weapon that can be situationally very useful: Soul Reaver +4 with that +2 Thac0 penalty on hit that lasts 20 rounds and stacks with itself, only few end game enemies have good Thac0 and enough hp to make it actually count, but you can make Ravager's Thac0 shitty with it and he has 534 hp and 75% resistance vs every weapon, a GWW and he will have a 10-20 worst Thac0 depending on how often your FMT hits and how he is lucky with his to hit rolls, an other GWW and the powerful Ravager will have the same Thac0 of a lev1 mage hitting you only on crits...
CF is a very good weapon in SoA, 1d10+3 damage, 5% chance to other 20 electric damages and stun if the enemy fails the save. In ToB the stun will happen less frequently as the enemies have better ST, still you get some and a +3 weapon can not hit very few enemies. For those you have to wait for the upgraded Hindo's Doom, and you can upgrade it only near the end of ToB, or use an other kind of weapon. An other useful katana is the Dak'kon's Zerth Blade, +2 and gives a spell slot more for the first 4 levels, I hated it before EE as unequipping it to use a ranged weapon or other reasons you did loose the memorizations, but in EE it is not an issue as long as it remains in a quick slot, it can be useful for Haer Dalis or the FMT if it sits permanently in the second MH quick slot, the OH one is better used for a +1apr weapon like Kundane and Belm, but the cost is more micro management as you have to go to the inventory screen to switch to a ranged weapon unless you use a returning dagger as MH weapon, then you simply switch from mlee to ranged in the main screen.
1d10 and the possibility that it stuns make CF a weapon that potentially can do a lot of stabbing damage and stun the enemy, but you have to be lucky as in the worst case it does only 1+3 damage and no stun, I prefer the staves as are more reliable for the stabs that matters, Striking and as you get Ram is the better one in every stab.
I rate the Flail of the Ages much higher then CF for his crushing damage type, the many elemental ones and the 30% chance, without save, so useful even in late ToB, to slow the enemy and Aerie has not enough apr to make it count. It is better used by the FMT with a +1 apr OH weapon, this way and with specialization and lev 13 you get 3.5 APR from the MH, later 4 with the right gauntlets, this means that the slow effect will happen often, even more often under improved haste. it is the better MH weapon for the FMT in your party IMHO, but it depends on how you use your pips, if you spare them for katanas CF can be an useful weapon in the stabs that are not worth to spend a charge of the Staff of Striking before you get Ram or in the not stabbing situations where you prefer to stun instead off slowing.
A FMT has a total of 10 pips to spend so choices are needed, specially if you want to spend 2 or 3 pips in DW style, with only 2 in that style you can reach specialization in only 4 weapons and the 4th late in the game. You can not have specialization in Celestial Fury, Staff of the Ram, Carsomyr, a ranged weapon and FoA and also pips in DW all at once so try to choose the weapon types that suit best to your own play style and that are more useful in the hands of Charname instead of the other party members. Haer dalis can get only proficiency so he can focus on more weapons, probably is better to give CF to him and have the FMT, that has more APR, use FoA, and this at the cost of having HD use only a +1apr weapon instead of 2.
But at the end the best possible build is not so crucial for your party, they have so many ways to protect themselves being all arcane casters and so many possible tactics that you can easily beat the game on insane without even touching CF, FoA and the Holy Sword, so make your choice according to what weapon you like and don't over think about it. I had more then one run with Aerie using FoA even if I know that is somehow wasted in her hands as she lacks of the apr to make it shine, in one of those runs I had Nalia self modded into a kensage and she was using CF, to give her FoA and a good mace or hammer to Aerie would had been better, but I liked the idea of a kensage Nalia with katana and the whiny elf CM with maybe the better weapon of the game, and it worked perfectly even if it was not the optimal choice...
https://sorcerers.net/Games/BG2/Walkthrough2/SoA/chapter-5/areas/ust-natha.php
at the point marked as 3 in the map in the link there is the Ust Natha bazar, from that page you can also access to the shop inventory of the 3 merchants. When you are in drow form you will also have a special price from the merchant located in the main Underdark area, the one near the point where you enter the area, the last merchant in the UD is in the Svirfneblin settlement.
Do you have a bag of holding? (You should.) Are you paying for any of it? (You shouldn't.) Then the answer is obvious - just loot all the good stuff from the merchants.
But all that drow junk that drops? Vendor trash, and not even at very high prices. You've got better than vanilla +3 weapons, and enchanted armor is a trap. And of course, you can't take any of it out of the Underdark.
Well, OK, the drow elven chain with improved casting speed is at least worth considering for temporary use. But you can get nearly the same AC and much better saves with archmage robes plus a protection item, and most of the major threats down in the Underdark are threats because of their save-or-lose abilities. Saves are a more important defense than AC.
I agree about the drow equipment that gets destroyed outside the Underdark, with few notable exceptions, the most noticeable one is the cloak that improves stealth that can be really powerful in the hands of a Stalker or Thief. In the original game I had my trusted ferret always stole it from me both before exiting the Underdark and transitioning from SoA to ToB, sadly that exploit does not work any more with the EE edition. It can still be pick pocketed early and give an edge in hiding and stabbing to the FMT in the Underdark.
But there is some really interesting not drow stuff in the Underdark that can be bought, shoplifted or looted.
1. all the scrolls and potions from the merchants in the drow city and in the Underdark in general, can be learned and erased for more xp or used in quick slots when the party decides to use armours and for the ones with lev7 or more can be used by Haer Dalis, the more Simulacrum scrolls he has the more he can have a clone that sing and uses the quick slots without expending what they contain while the original bard is still active, the clone can also go mlee with all the best equipment the party has (it can be returned to who normally uses, the bard must equip it only as he is calling the clone) and a shiny Black Blade of Disaster in the hand and how much TS srolls the party has in a quick slot.
2. the drow merchants sells Firetooth +3, the returning dagger, the Staff of earth +2 ( free earth elemental summon and free stone to flesh useful when flesh to stone is used to win a battle getting double xp) and Harbinger +3, a good 2H sword, but not better then Lilacor you can get way earlier. He sells also Sentinel +4 a shield that gives 5 points of AC and the Robe of Evil Archmage (your party needs UAI), +1 ST and 5%MR is always useful. Also Kaligun's Amulet of Magic Resistance, +10%MR and the Rod of Smiting, kills golems if they fail a save, can be useful.
3. items that can be looted or anyway obtained from encounters: Albruin +1, bastard sword useful for its passive protection from poison, Skull of Death and some very high level scrolls freeing, helping and then killing a certain mage, Dragon's Breath +4 a good halberd with 5 elemental damages (ok poison is technically not elemental but..), Soul Reaver +4 one of the best 2H swords in the game, each hit gives 2 point penality to Thac0, cumulative, Girdle of Frost Giant Strength 21 STR and needed if you want Crom later, Bracers of Blinding Strike 20 second of free Improved Haste, and a couple of good armours, but your party should not rely on them but in very particular situations.
Edit: al those things can be easily found in the walk trough I linked few posts ago, we are glad to help you, but learning how to fish yourself is better then getting fishes as presents from other players , if you want advice for tactics, builds or to solve a particular problem this is the right place to ask, but only doing your own research you will become a strong player and will develop your own play style. I have watched a lot of YT videos and read a lot of threads on this and other forums to learn, get new ideas and inspiration, other people like @jmerry had even looked into the technical aspect of the game with modding tools, I did not went to that point, but I did always try to develop my own style, to have other people tactics only as a starting point from which I could find my own way to play the game.
Albruin's a tricky one to get; it comes from one of the encounters in that soul trap device, and the only way to get it is to cast Heal on the crazy high-level mage who's trying to kill you. All for a sword that was good in BGEE but is now just a utility piece? No, thanks. Sure, a source of poison immunity and 1/day Detect Invisibility is nice, but it's not worth the trouble of risking getting Imprisonment cast on you.
With a party all arcane casters so all able to cast spell immunity: abjuration I would say that Imprisonment is not so scary, but I see your point, for many parties the risk is more then the gain. Aerie with RoV and AoP can cast heal very fast.
Poison immunity is very rare, no mage or cleric spell grants it and there are few items that do it, it can be really useful when many cloudkills are stacked to disrupt casters, kill minor foe and reduce the hp of the other enemies.
You cast Mislead and hide your clone away from the enemy and you have a form of invisibility that can not be dispelled, even if they manage to see you casting True Sight after a split second you are again invisible, the same if you make an attack or an other action that would have broken the invisibility.
if you cast Mislead with all your 3 arcane casters party you are able to attack the enemy without retaliation, they simply stay there and take the damage, if your FMT uses it and attacks from the back of the enemies all his attacks will be back stabs if he uses a weapon that can stab and your party will be immune to spells on target, the enemy mages will be only able to cast AoE damaging spells like Fireball, if the AI is clever enough to do it, which in most of the battle scripts is not the case.
Isn't it OP? Attacking with no retaliation and infinite stabs without any effort, all you must do is to hide your clones as killing them or dispelling them trough spells interrupts the invisibility.
It is so powerful that I choose to almost never use it, specially with a party where all can cast it, it makes every battle vs enemies that can not naturally see trough invisibility almost as easy as spamming ctrl-Q. I strongly suggest you to avoid the abuse of that spell, you can have sometimes fun with it, why not, maybe having your FMT clearing a dungeon with stabs, once is fun to do, every time completely takes out the challenge, so the fun of the game.
Mordenkainen's Sword, is immune to all physical and elemental damage, can be damaged only with magical damage (like magic missile, skull trap and ADHW), very good tank that can deal also some damage.
Skeleton Warrior, has 90% magic resistance and 50% resistance to piercing and slashing, lasts a very long time, comes from the Animate Dead spell if the caster is lev15 or more, Aerie can get it also with the divine spell that has the same name and is a lev3 spell while the arcane version is lev5, also with it lev15 is needed to get the warrior instead of few regular skeletons.
The Elementals, better from the cleric as a mage has to fight a mental fight of 3 rounds and if he looses it the elemental is hostile, the one from the cleric is always friendly and there is no mental fight. The fire elemental is useful vs beholders and other foe, the earth one is more mlee capable. the Cleric can only summon elementals from the lev 7 HLA but they come in the most powerful version and 2 of them in 69% of the cases, for the other 31% an elemental prince is gated and he is far better then the 2 elementals, I usually avoid the elementals summoned by mages, but it is an option in some situations where you can prepare for the battle so can waste the time for the mental fight and maybe to kill the elemental if he becomes hostile.
Aerial Servant, cleric only, 16 HD and immune to normal weapons.
Planetar (arcane, more powerful) and Deva (divine, less powerful but still very good), only Aerie can call them in your party as the Blade and the FMT never reach lev9 spells.
The Planetar and the Deva can not exist at the same time or in multiple, you can have only one, but they can coexist with the Elemental Prince. If you want the maximum you can get as summons for your party Aerie has to put 3 divine Elemental Summoning in a CC, you have a very high chance that the Elemental Prince spawns (no regular elementals spawn if this happens) or in the worst case 5 elementals spawn. If you get the Prince then she can gate a Planetar or a Deva and 3 Mordy swords or Skeleton Warriors depending on the situation. It is very costly slots wise, but you can cast the CC then rest to memorize again so she will not go to the battle with her high level slots depleted, if you do so be sure that you rest right before the tough battle as you will put enemy seen as condition to trigger the CC and you don't want that the Elemental Prince is wasted fighting minor foe.
Last but not least Spider Spawn, it remains OP even at high levels if combined with stacked webs, you have to stack more webs then at lower levels as the enemies have better ST, but if you stack enough of them even high level enemies will fail the save and once they are stuck in the web every hit is automatically successful ignoring Thac0 and AC, so your trusted spiders, that are immune to web, will hit and often poison the enemies.
Maybe I forgot some summon, but that should be all.
All the other summons are basically trash, you can use them as cannon fodder to buy you some time or to suck that Death spell that other way would had killed your good ones, but outside the LoB difficulty will not make a real difference in the battle, use the charges from the wand to call them, don't waste slots.
Depends on your class. The usual evil party members are: Korgan (best fighter), Dorm (also good but Korgan is better IMHO), Viconia (cleric), Edwin (mage), Hexxat (thief). Jan (mage/thief) is neutral and can also work. You need someone to cast magic, someone to fight, someone to do thievery, and ideally someone to cast divine magic but it is in fact optional.
Depending upon your class, you can mix and match from the above. It helps in smallish parties to be multiclass to share class jobs. For example, if you play a fighter/thief then you could take Korgan and Edwin. If you play a fighter/mage you could take Korgan and Hexxat/Jan. Playing an assassin you could take Korgan and Jan or Korgan and Viconia. How you mix and match is endless and part of the appeal of replaying.
Above you asked about longswords and scimitars. Check out https://baldursgate.fandom.com/wiki/Category:Long_swords and you can learn about all the weapon types and come back with questions. Generally the 'best' is available later in the game and there are progressions of weapons available as you adventure and play the game. Longswords have many, many options and are versatile. Scimitars have very good options including Belm early and some good ones later.
Comments
It can be used by both of them if MR is needed and also for the 3 Dispel Magic charges, DM at lev 15, so not so effective vs the late game bosses, while the DM on hit is at lev 30, but all your party can use the SotM that also has DM at lev 30 on hit + very useful protections.
Carsomyr deals 1d12+5 (slashing), +5 extra vs. chaotic evil and gives -5 Thac0, SotM deals 1d6 +1 (crushing) and gives only -1 Thac0 even if both are +5 for the enemies they can hit, Ram +4 deals 1d6 +10 (crushing), when upgraded becomes +6 dealing 1d6 +12 (crushing)+1d4 extra (piercing) and has 10% chance (15% the +6 one) to knock back the enemy and stun him, something that some players hate, but I find pretty useful in a small party as sends away temporarily an enemy when many are around or buy you some time to do free ranged damage when you are facing a single enemy.
As Crushing is better then slashing, less resisted, and Ram is a more reliable and effective way to deal damage my FMT was using it as main damaging weapon, switching to Carsomyr only when dispel on hit or MR was needed, but still Carsomyr can be really useful i.e. you don't want your enemy thrown away when you are using GWW and with GWW and the dispel on hit and damage of the holy sword a FMT can carve trough a WK dragon in a round taking down his protections with the first hit and his hp with 6.5(on average)+5+STR bonus+5(if he is CE) attacks, he will fall before he can react, battle won without using a single spell, I have done it.
So if your FMT has pips to spend in 2Hsword to use it is not a bad idea at all, but you can live without it as the SotM covers the dispel on hit and Ram is just as good, if not better, to deal damage.
Haer Dalis will better use weapons that allow DW, better +1 apr weapons or weapons that have other powerful effects like Blackrazor, I really don't see him using Carsomyr as main weapon as he will lack of APR with it. He can still equip it if MR is needed to survive, equipping it and then the ring of Gaxx and singing he gets 70%MR, but as he can use spell immunity it is very situational. He can also use it to dispel on hit with better thac0 then with the SotM.
If your FMT will spend pips in 2Hsword there is an other weapon that can be situationally very useful: Soul Reaver +4 with that +2 Thac0 penalty on hit that lasts 20 rounds and stacks with itself, only few end game enemies have good Thac0 and enough hp to make it actually count, but you can make Ravager's Thac0 shitty with it and he has 534 hp and 75% resistance vs every weapon, a GWW and he will have a 10-20 worst Thac0 depending on how often your FMT hits and how he is lucky with his to hit rolls, an other GWW and the powerful Ravager will have the same Thac0 of a lev1 mage hitting you only on crits...
1d10 and the possibility that it stuns make CF a weapon that potentially can do a lot of stabbing damage and stun the enemy, but you have to be lucky as in the worst case it does only 1+3 damage and no stun, I prefer the staves as are more reliable for the stabs that matters, Striking and as you get Ram is the better one in every stab.
I rate the Flail of the Ages much higher then CF for his crushing damage type, the many elemental ones and the 30% chance, without save, so useful even in late ToB, to slow the enemy and Aerie has not enough apr to make it count. It is better used by the FMT with a +1 apr OH weapon, this way and with specialization and lev 13 you get 3.5 APR from the MH, later 4 with the right gauntlets, this means that the slow effect will happen often, even more often under improved haste. it is the better MH weapon for the FMT in your party IMHO, but it depends on how you use your pips, if you spare them for katanas CF can be an useful weapon in the stabs that are not worth to spend a charge of the Staff of Striking before you get Ram or in the not stabbing situations where you prefer to stun instead off slowing.
A FMT has a total of 10 pips to spend so choices are needed, specially if you want to spend 2 or 3 pips in DW style, with only 2 in that style you can reach specialization in only 4 weapons and the 4th late in the game. You can not have specialization in Celestial Fury, Staff of the Ram, Carsomyr, a ranged weapon and FoA and also pips in DW all at once so try to choose the weapon types that suit best to your own play style and that are more useful in the hands of Charname instead of the other party members. Haer dalis can get only proficiency so he can focus on more weapons, probably is better to give CF to him and have the FMT, that has more APR, use FoA, and this at the cost of having HD use only a +1apr weapon instead of 2.
But at the end the best possible build is not so crucial for your party, they have so many ways to protect themselves being all arcane casters and so many possible tactics that you can easily beat the game on insane without even touching CF, FoA and the Holy Sword, so make your choice according to what weapon you like and don't over think about it. I had more then one run with Aerie using FoA even if I know that is somehow wasted in her hands as she lacks of the apr to make it shine, in one of those runs I had Nalia self modded into a kensage and she was using CF, to give her FoA and a good mace or hammer to Aerie would had been better, but I liked the idea of a kensage Nalia with katana and the whiny elf CM with maybe the better weapon of the game, and it worked perfectly even if it was not the optimal choice...
at the point marked as 3 in the map in the link there is the Ust Natha bazar, from that page you can also access to the shop inventory of the 3 merchants. When you are in drow form you will also have a special price from the merchant located in the main Underdark area, the one near the point where you enter the area, the last merchant in the UD is in the Svirfneblin settlement.
But all that drow junk that drops? Vendor trash, and not even at very high prices. You've got better than vanilla +3 weapons, and enchanted armor is a trap. And of course, you can't take any of it out of the Underdark.
Well, OK, the drow elven chain with improved casting speed is at least worth considering for temporary use. But you can get nearly the same AC and much better saves with archmage robes plus a protection item, and most of the major threats down in the Underdark are threats because of their save-or-lose abilities. Saves are a more important defense than AC.
But there is some really interesting not drow stuff in the Underdark that can be bought, shoplifted or looted.
1. all the scrolls and potions from the merchants in the drow city and in the Underdark in general, can be learned and erased for more xp or used in quick slots when the party decides to use armours and for the ones with lev7 or more can be used by Haer Dalis, the more Simulacrum scrolls he has the more he can have a clone that sing and uses the quick slots without expending what they contain while the original bard is still active, the clone can also go mlee with all the best equipment the party has (it can be returned to who normally uses, the bard must equip it only as he is calling the clone) and a shiny Black Blade of Disaster in the hand and how much TS srolls the party has in a quick slot.
2. the drow merchants sells Firetooth +3, the returning dagger, the Staff of earth +2 ( free earth elemental summon and free stone to flesh useful when flesh to stone is used to win a battle getting double xp) and Harbinger +3, a good 2H sword, but not better then Lilacor you can get way earlier. He sells also Sentinel +4 a shield that gives 5 points of AC and the Robe of Evil Archmage (your party needs UAI), +1 ST and 5%MR is always useful. Also Kaligun's Amulet of Magic Resistance, +10%MR and the Rod of Smiting, kills golems if they fail a save, can be useful.
3. items that can be looted or anyway obtained from encounters: Albruin +1, bastard sword useful for its passive protection from poison, Skull of Death and some very high level scrolls freeing, helping and then killing a certain mage, Dragon's Breath +4 a good halberd with 5 elemental damages (ok poison is technically not elemental but..), Soul Reaver +4 one of the best 2H swords in the game, each hit gives 2 point penality to Thac0, cumulative, Girdle of Frost Giant Strength 21 STR and needed if you want Crom later, Bracers of Blinding Strike 20 second of free Improved Haste, and a couple of good armours, but your party should not rely on them but in very particular situations.
Edit: al those things can be easily found in the walk trough I linked few posts ago, we are glad to help you, but learning how to fish yourself is better then getting fishes as presents from other players
Poison immunity is very rare, no mage or cleric spell grants it and there are few items that do it, it can be really useful when many cloudkills are stacked to disrupt casters, kill minor foe and reduce the hp of the other enemies.
if you cast Mislead with all your 3 arcane casters party you are able to attack the enemy without retaliation, they simply stay there and take the damage, if your FMT uses it and attacks from the back of the enemies all his attacks will be back stabs if he uses a weapon that can stab and your party will be immune to spells on target, the enemy mages will be only able to cast AoE damaging spells like Fireball, if the AI is clever enough to do it, which in most of the battle scripts is not the case.
Isn't it OP? Attacking with no retaliation and infinite stabs without any effort, all you must do is to hide your clones as killing them or dispelling them trough spells interrupts the invisibility.
It is so powerful that I choose to almost never use it, specially with a party where all can cast it, it makes every battle vs enemies that can not naturally see trough invisibility almost as easy as spamming ctrl-Q. I strongly suggest you to avoid the abuse of that spell, you can have sometimes fun with it, why not, maybe having your FMT clearing a dungeon with stabs, once is fun to do, every time completely takes out the challenge, so the fun of the game.
Skeleton Warrior, has 90% magic resistance and 50% resistance to piercing and slashing, lasts a very long time, comes from the Animate Dead spell if the caster is lev15 or more, Aerie can get it also with the divine spell that has the same name and is a lev3 spell while the arcane version is lev5, also with it lev15 is needed to get the warrior instead of few regular skeletons.
The Elementals, better from the cleric as a mage has to fight a mental fight of 3 rounds and if he looses it the elemental is hostile, the one from the cleric is always friendly and there is no mental fight. The fire elemental is useful vs beholders and other foe, the earth one is more mlee capable. the Cleric can only summon elementals from the lev 7 HLA but they come in the most powerful version and 2 of them in 69% of the cases, for the other 31% an elemental prince is gated and he is far better then the 2 elementals, I usually avoid the elementals summoned by mages, but it is an option in some situations where you can prepare for the battle so can waste the time for the mental fight and maybe to kill the elemental if he becomes hostile.
Aerial Servant, cleric only, 16 HD and immune to normal weapons.
Planetar (arcane, more powerful) and Deva (divine, less powerful but still very good), only Aerie can call them in your party as the Blade and the FMT never reach lev9 spells.
The Planetar and the Deva can not exist at the same time or in multiple, you can have only one, but they can coexist with the Elemental Prince. If you want the maximum you can get as summons for your party Aerie has to put 3 divine Elemental Summoning in a CC, you have a very high chance that the Elemental Prince spawns (no regular elementals spawn if this happens) or in the worst case 5 elementals spawn. If you get the Prince then she can gate a Planetar or a Deva and 3 Mordy swords or Skeleton Warriors depending on the situation. It is very costly slots wise, but you can cast the CC then rest to memorize again so she will not go to the battle with her high level slots depleted, if you do so be sure that you rest right before the tough battle as you will put enemy seen as condition to trigger the CC and you don't want that the Elemental Prince is wasted fighting minor foe.
Last but not least Spider Spawn, it remains OP even at high levels if combined with stacked webs, you have to stack more webs then at lower levels as the enemies have better ST, but if you stack enough of them even high level enemies will fail the save and once they are stuck in the web every hit is automatically successful ignoring Thac0 and AC, so your trusted spiders, that are immune to web, will hit and often poison the enemies.
Maybe I forgot some summon, but that should be all.
All the other summons are basically trash, you can use them as cannon fodder to buy you some time or to suck that Death spell that other way would had killed your good ones, but outside the LoB difficulty will not make a real difference in the battle, use the charges from the wand to call them, don't waste slots.
Which are the best longswords and scimitars in the game?
Depends on your class. The usual evil party members are: Korgan (best fighter), Dorm (also good but Korgan is better IMHO), Viconia (cleric), Edwin (mage), Hexxat (thief). Jan (mage/thief) is neutral and can also work. You need someone to cast magic, someone to fight, someone to do thievery, and ideally someone to cast divine magic but it is in fact optional.
Depending upon your class, you can mix and match from the above. It helps in smallish parties to be multiclass to share class jobs. For example, if you play a fighter/thief then you could take Korgan and Edwin. If you play a fighter/mage you could take Korgan and Hexxat/Jan. Playing an assassin you could take Korgan and Jan or Korgan and Viconia. How you mix and match is endless and part of the appeal of replaying.
Above you asked about longswords and scimitars. Check out https://baldursgate.fandom.com/wiki/Category:Long_swords and you can learn about all the weapon types and come back with questions. Generally the 'best' is available later in the game and there are progressions of weapons available as you adventure and play the game. Longswords have many, many options and are versatile. Scimitars have very good options including Belm early and some good ones later.