Arnon's Hunger

The hand crossbow is carved from a blighted tree and provides the user with a +2 bonus to attack rolls and damage.
The crossbow provides +1 health points for every celestial, fey or humanoid killed for a maximum of 20 points. This well of saved hit points can be used in part or as a whole to heal the user at any point as an action, similar to a Paladin's Lay On Hands.
The user must kill at least one of the aforementioned creatures per day or suffer -10 health points to their overall hit points, per day, or until the user dies. The lost health points can only be returned by a Greater Restoration spell, a Transmutation Wizards' Master Transmuter, or by a Remove Curse spell which removes the curse from the weapon; this removal of the curse also removes the well of saved health points, leaving the user with a +2 hand crossbow.