Unholy Weapon

Weapon (any weapon), rare

You gain a +1 bonus to attack and damage rolls made with this weapon. When you hit a good celestial or dragon with it, that creature takes an extra 2d6 necrotic damage. (At the Gm’s discretion, certain particularly good creatures such as paladins might take this damage even if they are not celestials or dragons.)

Unholy weapons are usually crafted with icons, runes, or symbols from an evil-aligned deity, chaos cult, or other organization that actively wants to promote evil and destroy good.