Fane-Eater

From Baldur's Gate: Descent into Avernus, page 223.

Description
''Weapon (battleaxe), legendary (requires attunement by an evil cleric or paladin). 4 lbs.''

Fane-Eater is a battleaxe belonging to Arkhan the Cruel.

You gain a +3 bonus to attack and damage rolls with Fane-Eater. If you attack a creature with this weapon and roll a 20 on the attack roll, the creature takes an extra 2d8 necrotic damage, and you regain a number of hit points equal to the necrotic damage taken.