An evil half-orc can get a natural 25 str by the end of the game. An evil non-halfling can get 24, and an evil halfling can get 23.
It's not a matter of strength, it's a matter of size. It doesn't matter how strong you are, it's how big you are. Frost-giants can wield 2hd swords one-handed because they're huge creatures (2 steps larger then humans).
You'd be causing damage to your body or potentially destroying the weapon with every swing, due to forcing weight on areas it normally shouldn't touch. Or you'd need some tactile telekinesis to help offset the load distribution.
If however, you had a suit of magical armor that could re-enforce your body, to help compensate for off balanced weight load, or physically make you large enough to wield the weapon that way more naturally, it's quite do-able.
The Large Metal Unit makes you pretty big if I'm not mistaken. Maybe it could work in that?
@cheesebelly I just wanted to add, that in general katanas are heavier and broader than longswords. The common missconception results from longsword having a big range in weigth and broadness. But overall the katana is heavier and thicker.
Katana are also, almost always, used two-handed style. Dual-wielding is EXTREMELY rare. A Samurai daisho was mostly for convenience sake. Long blade for outdoor fighting, small blade for indoor fighting, and because it was improper for a warriors to be fully stripped of weapons when visiting a home.
And technically, even long swords should used two-handed....an Arming sword is actually the step above a short sword, then a bastard sword, then longsword/katana, then great swords.
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And technically, even long swords should used two-handed....an Arming sword is actually the step above a short sword, then a bastard sword, then longsword/katana, then great swords.