LuckLeech Dagger (3.5e Equipment)
From D&D Wiki
This +1 deadly dagger is worked with a carving of a pair of dice at its hilt‘s center. Once per minute, it can draw forth the ebbing life force of a creature and convert it into good fortune towards any of its attacks. The dagger must deal the final damage that kills a creature in order for its life force to be absorbed. Each creature killed this way grants the dagger’s wielder a reroll on any one attack roll made for the dagger. It is possible to reroll an attack roll for as many rerolls the dagger contains. The result of the final reroll must be taken by the dagger’s wielder, even if its worse than any before it. The dagger may store up to five attack rerolls. (When randomly rolled, a luckleech dagger contains 1d6-1 rerolls, minimum 0).