Ghostbind

Weapon (longsword), legendary (requires attunement)

This weapon is a +1 longsword, but has one unique property when used to fight shades. If a shade is impaled on the sword, the shade is incapacitated. The shade remains in this state until the sword is removed or the shade is slain. No undead creatures are able to touch this weapon, even if it is unattended. Impaling a shade requires making a critical hit against it.