The Sword of Night is a powerful magical item that has been passed down by the generations of Nightmaster. The sword has the automatic abilities of warning its owner of danger, compelling people to tell him the truth and keeping the owner young and at peak fitness. Some of it's powers are dependent on the owner's belief (as it has been shown to take different shapes and multiply) and cut anything the Nightmaster believes it can cut, although the full extent hasn't been shown yet.

Other Media

Constantine

In the episode "Rage of Caliban", Chas Chandler picks up the sword and begins telling John of his troubles, before Constantine informs him the Sword of Night is making him confess the truth.