God Slayer (3.5e Equipment)
From D&D Wiki
Ironically named, this weapon is incapable of slaying a real god. Forged while the world was new after the creation of the kittelic race by the moon daughters, the mortal races were superstitious. They could not grasp the power behind their nine lives and thought they were immortal, thus gods. It is unsure how the dagger came into existence, but many believe a clever wizard, learning the truth behind the kittelars, enchanted a dagger with the ability to kill a kittelar once and for all in one death strike. Most likely taking the guise of a holy cleric, he presented the dagger, claiming it can kill gods and for a small donation, he can forge more. In the tale, he made it rich that, but he suffered divine punishment for impersonating a cleric.
Game Rule Information
Any creature that sustains it's life through stealing souls into its body and is dealt a killing blow with this dagger must make a Fortitude Save with a DC equal to 20 + its HD or else be slain, the souls trapped in his body released.