Homebrew Help Req: Villainous Thief

[AtlasSniperman]

Hey folks!
I realise just how old 3.5 is, so Homebrew on request might be a little hard to arrange, but here goes.

Currently running a game and have a great idea for a villain; I love the idea that he can copy/steal the abilities from other people(class abilities clearly. with specific spells being unique abilities rather than spellcasting in general) and storing these abilities in Daggers. When he uses a dagger, he gains access to the ability.

e.g. Throwing the dagger of Translocation(Dimension Door) and he teleports to where it would land.
Dagger of gravity(Monks Slow Fall) can be pressed against a wall as he falls to slow the falling
ShankyShank(Sneak attack) can deal sneak attack damage despite him not having it. etc

I know I could just give him this ability, it is my perogative as GM. However I prefer the idea of it being structured and having its own limitations etc and would really like some help coming up with some balance so I don't feel like a bad GM just plucking stuff from the other side.

[noob]

Refluffed itilidth savant that ate the brain of a level 18 factotum and of a high level spellthief.