Darkblade

Weapon (greatsword), legendary (requires attunement)

This weapon’s blade emits black wisps of smoke. While you hold the weapon, as a bonus action you can cause all sources of light within 60 feet of you to only emit 5 feet of light for 1 hour. Additionally, darkness in the affected area becomes magical darkness in which you can see as long as you are attuned to the darkblade. Finally, when you hit a creature completely within darkness with the weapon, the weapon deals an additional 2d6 slashing damage.