Night's Edge

The Night's Edge is a high-end melee weapon, crafted at a Demon Altar. It requires four of the currently most powerful sword-class weapons to craft: a Light's Bane, a Muramasa, a Blade of Grass, and a Fiery Greatsword.

The Night's Edge has the same lighting effect as the Fiery Greatsword as when swung it creates light, but it seems the effect is less bright and does not last as long.

Putting any of the above four weapons in the Guide's "Crafting" option will reveal the full recipe and Demon Altar requirement.