In response to Uthunan's comments that have been added to his entry:
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IC is a practical optimization contest, and has an elegance category specifically because rules abuse is frowned upon. The rules do state that you can make a cheesy dish, sure, but in my mind that means something that would actually work. I really don't think any reasonable DM would ever look at that rule and go "If you are wielding someone as a weapon and roll a natural 1, the weapon breakage clause of improvised weapons clearly means that they DIE INSTANTLY, no save." Read it out loud and tell me it doesn't sound ridiculous.
Death in D&D is very specific; you become dead when something makes you "die" or go to -11 hp. That's it. If the ability caused an amount of damage to the improvised weapon, you'd have a case. If you'd argued that the person being wielded should take some damage, I would have said, "It's not RAW, but that makes sense and it's funny." But purposely fishing for natural 1's/20's to try an exploit a loophole that isn't even there is why I scored it so low.