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.
Proficiency with a battleaxe allows you to add your proficiency bonus to the attack roll for any attack you make with it