I think some people should check out http://www.myarmoury.com/feature_oakeshott.html , just for y'know frame of reference, historically speaking that is.

(Yes, I know this is a fantasy game. However, as someone before me stated, it should at least strive for believability if not chore-laden realism.)

Think of this in a pen and paper game :
Player : 'Cool, a new Elven Claymore, I'll use that in my left hand, and the Dwarven in my right, fighting with both.'
DM : 'You can't, to swing a claymore in one hand, you need the other one not attacking, but helping your balance.'
Player : 'Ok, I'll use the Elven, right hand only.'
DM : [rolls die] 'A spider drops from the ceiling, luckily it misses you.'
Player : [rolls die] 'Attack the spider, one handed claymore swing.'
DM : 'Hit, you kill the spider easily, but your weapon hits the stone floor hard.' [rolls die] 'Ooh, bad luck, you just broke your wrist, the pain is excruciating, you drop the claymore.' [rolls dice] 'Six more spiders drop from the ceiling..........

Awesome.