True Night's Edge

The True Night's Edge is the third strongest sword in Terraria, beaten only by the Terra Blade and The Horseman's Blade.

It shoots a large light blade similar in appearance to the Night's Edge forward on attack. This ability has a short cooldown, so if the sword is being swung rapidly not every swing will fire a glowing sword. If you're standing right next to a solid wall or door which is only one block thick then the fired glowing sword can pass through it. However, it can't pass through the ceiling or floor.

Trivia

 * The True Night's Edge does more damage than the True Excalibur, yet the Night's Edge does less damage than the Excalibur.
 * The True Night's Edge and the Night's Edge itself could be a reference to the Soul Edge, a sword in the Soul Calibur series which represents true evil and its counterpart, Soul Calibur, represents true good, which would be the Excalibur and True Excalibur in this case.