I stole them from the Curst blacksmith thinking they'd make a good weapon for Annah..but she can't wear them. Is she supposed to be able to?

What does it say in their item description? Weapons usually state which characters can use them.

Assassin's Knuckles 1-10 Piercing +3 Causes Stunning, Silence and Poison +3 1 1 Thieves Buy from the blacksmith, Crumplepunch (Outer Curst)

source: http://shrines.rpgclassics.com/pc/planescape/weapons.shtml

Sounds like she should be able to use them. Is there a Alignment (Good/Evil) requirement on them? That site doesn't list one though..

I just looked at the item file, and yes, Annah is prohibited from using them. They can only be used by TNO while he's a thief. Basically, even though they're fist weapons, they are brass knuckle variants and not punch daggers. Annah can't use any of the knuckle or gauntlet weapons, she can ONLY use punch daggers.

Okay thanks for the help. :)