Elliot's signature weapons, "The Executioners" are custom-built, handgun-sized, revolving shotguns. He was not the one who named the weapons (and in fact he never refers to them as "Executioners"). Much like his nickname, The Revenant, the firearms' names come from their sinister reputaiton.
According to Elliot, the weapons were, "Custom built - by an old friend," although he has never gone into detail regarding the identity of the manufacturer. They are one-of-a-kind, firing powerful 12 guage shells from revolving cylinders (which hold a measly four shells each). Lacking any kind of shock absorption, the shooter's wrist takes the brunt of the force when firing. At one point, Logan Farrell shoots an Executioner in self defense, and while he kills his attacker, his wrist is literally shattered in the process. He later questions how Elliot is capable of firing two such weapons on a regular basis.
Along with his M13 Intervention, a fully equipped Elliot is a terrifying force on the battlefield. The Executioners, while ineffective at medium and long range, are lethel at close range - where Elliot is most efficient in any case.