Muramasa

The Muramasa is a glowing blue sword that is only found in treasure chests in the Dungeon. Unlike most weapons, you can hold down the left mouse button and it will keep swinging.

The Muramasa has a slightly longer reach than a Phaseblade. It deals 22 damage and has a Fast attack speed. When used, it will create a small bit of light, useful for unlit caverns or dungeons.

A good tactic is to use the weapon in conjunction with a full set of Shadow Armor/Cobalt Armor and Feral Claws to give it an incredibly fast swipe speed which allows you to cut through virtually any enemy with relative ease.