Sometimes these weapons are found in the hands of Orrish, looted from the Fallen East currently part of the Darklands.
d20 [specific] Requirements:
Extra +d4/2 base! Radiant damage (2/4/8). Any sort of Radiant attack (including ranged) can have its total damage reduced by an amount equal to their Attack bonus by expending their Reaction. It is immune to Radiant and Necrotic damage of any kind. It is immune to non-magical fire (if the weapon is lit on fire, it will do a +d4/2 damage) and acid as well as all forms of rust/corrosion. Each year (start) the wielder must make a DC 20 Constitution save or take 1 HP of permanent radiant damage – no recovery/no resistance/immunity.
After attunement, the light shed reflects the wielder’s nature. Violet = evil, white = good, blue-white = neutral. Attunement is DC 20 Constitution or d4 radiant (no recover/resist/immune) + 1 malaise (-1hp max) until Long Rest.
Cleaning it with fire will produce an oily smoke in a 20m radius for 5 rounds that causes d4 poison damage unless a DC 14 Constitution Save is made.