I have played BG2 for 3 times now and i always find in the irenicus kitchen (the place of Illych) a broken sword that I keep and keep but never seem to work for sth... does anybody know what is it useful for ???

it doesnt do anything.... it is just a sword that the dwarves was going to repair but somehow didn't have the time and got stopped :D
use the bastard sword +1 that you get more into the dungeon in that way

In fact somethimes regular swords broke. Enchanted ones don't.

Yeah, it seemed like things broke all the time in BG1 cause of the sabo.

I don't even think I ever noticed there was a broken sword in the dungeon. Good find!

I'm no sure but maybe you can brake your normal weapon if you do a critical miss...

I think that main reason why weapons rarely broke in BG2 is that you find good +1/+2 weapons early in the game.