Crystal Sword (5e Equipment)
From D&D Wiki
Weapon (longsword), very rare (requires attunement by a non-evil character)
This magic longsword is comprised of a semitransparent, lightweight crystal. Myths and legends tell it holds the power to destroy evil.
Any hit with this weapon deals an extra 2d8 radiant damage. Unlike a normal longsword, its lightweight composition and aerodynamic design grants it the finesse and thrown (20/60) weapon properties.