Twice in the series, an Arwen 37 Grenade launcher of unknown type was show.
The ARWEN 37 is a less-lethal launcher which fires 37 mm less-lethal rounds (foam or wooden or tear gas payload) designed for riot control. It has a 5-round rotary drum magazine. "ARWEN" is an acronym for "Anti Riot Weapon ENfield".
Originally this weapon in real life is supposed to be a less than lethal launcher that would fire tear gas among other types of less than lethal ammo, but in the series it fired actual grenades, creating large explosions.