That's pretty clever, and even sounds overpowered (though probably unneeded in most fights that would benefit from this trick). I do like the concept of "reverse pickpocketing." I think a cooler tactic would be to replace a healing potion with a poison potion and have a character hurt or kill himself drinking the potion. They'd have to program that in though. It would also be neat if replacing an item you've stolen from someone with an item of equal weight (and perhaps of similar shape or type) would reset the total weight value that you could steal.
