This is a skin for the Eoka Pistol item. You will be able to apply this skin when you craft the item in game.
The Eoka Pistol is a very cheap, very ineffective, and very unreliable firearm. It fires shotgun ammunition in a wide arc, and is capable of killing opponents in one hit (however unlikely that is).
The Eoka pistol consists of a spent 20mm cartridge with a small hole on top attached to a crude wooden frame. A shotgun shell is loaded into the 20mm shell, and a stone is scraped across the hole on top to produce a spark to fire the weapon.