Yeah most NPCs have those quirks and extra bonuses.
Faldorn summons dread wolves, Quayle casts invisibility via special ability, Tiax can summon ghasts, Branwen can create spiritual hammer, Yeslick can cast dispel magic, Eldoth has poison arrows, Coran and Kagain have illegal stats and Coran has illegal weapon proficiencies, Alora has her rabbit foot, Imoen and Shar-teel can dual class, Safana has charm ability, Viccy has globs of magic resitance, Minsc has berserk and illegal stats (and Boo, how can I forget Boo!?), Dynaheir can slow poison, Edwin is the best mage thanks to his amulet, Neera comes with her dowry err gem bag, Dorn has illegal class, Rasaad has his spiffy boots...Garrick has...um, unless I am horribly mistaken, nothing. Khalid too, although he has lower morale than most, which is his quirk, I suppose. Jaheira has nothing but gets 'Harpers call' spell (and can get a certain other Harper related powerful item) in BG2 at least. Xzar and Montaron are just generaly so awesome that they don't need quirks. Heh.
I still don't find it "special", it's just how the game mechanics work. It's also not "special" that Monty is a multi class. If anyone, Xzar is "more special" because (with tomes) he can dual to two classes. Most people plan their dual class ahead and distribute points to be efficient in their starting class and then their dualled class, where Xzar can be efficient in 3. It's still possible for a player to do that, but it's more special than an NPC with the option to dual to one class.
Comments
"...Brave, brace sir Garrick, sir Garrick run away..."