Lifeshank (DnD Equipment)
From D&D Wiki
The lifeshank gives the wielder free use of the Lingering Damage feat, even if he does not meet the prerequisites and increases his sneak attack damage to +38d6. The dagger scores a critical hit on a 7-20/x10. The sneak attack damage is multiplied. Anyone Lifeshank has scored a critical hit on takes a number of negative levels equal to the wielder's character level. Anyone successfully hit by Lifeshank permanently turns a pink color, suffering a -40 to hide checks.
Any damage dealt by Lifeshank is also directed to the wielder, who suffers half the total damage. Anyone who is not at least a 20th level rogue who wields Lifeshank suffers a number of negative levels equal to the weapon's total enhancement bonus.
Lifeshank is said to have been made when Gond and Mask got really drunk one night and decided to make a joke weapon. It is said to be hidden somewhere in the Underdark of Toril and can only be destroyed by the use of a Wish spell cast by 10,000 celestials and 10,000 devils working for the express purpose of destroying the weapon while under the direct observation of a greater deity.