From Destinypedia, the Destiny wiki
Projection Rifle Cabal Frag Detonator
Steal Relic High Durability Rapid Movement Limited Flight Strafe Thrusters Cabal Melee
Standard Liberators are a more powerful variant of the Legionary appearing in the Leviathan Raid.
Standard Liberators are capable of recovering lost or stolen keys that unlock the doors that lead to different sections of the Raid. They are a high priority target for this very reason.