Defiled Vindicator (5e Equipment)
From D&D Wiki
Weapon (any sword), legendary (major) (requires attunement by a paladin of evil alignment)
While the Defiled Vindicator certainly shares origins with the holy avenger, they are more intertwined than most know. Through horrid ritual and sacrifice, the normally celestial nature of these blades are tainted and warped, much like the blades themselves as they grow spines and lose color.
You gain a +3 bonus to attack and damage rolls made with this magic weapon. When you hit a celestial or humanoid with it, that creature takes an extra 2d10 necrotic damage.
While you hold the drawn sword, it creates an aura in a 10-foot radius around you. All hostile creatures in the aura have disadvantage on saving throws against spells you cast. If you have 17 or more levels in the paladin class, the radius of the aura increases to 30 feet.