Blade of Crota
From Destinypedia, the Destiny wiki
The Blades of Crota are a group of unique Knights, that appears in The Dark Below. Blades of Crota appear on Earth and the Moon every ten minutes in public spaces, accompanied by a few small waves of Acolytes. A Blade will also appear after the encounter with Omnigul in Fist of Crota. Blades are always protected by an Arc shield, but are otherwise fairly low-level and easy to kill. Killing a Blade will drop an Ascendant Sword, allowing the player to fight with a sword for a little less than a minute. On rare occasion, they'll drop Husk of the Pit, a common-level weapon that can be upgraded to become Eidolon Ally and then Necrochasm.
List of appearances