The A.R.C. Repair Arm is a Robotics' Specialty device. It allows the Robotics' to speed the deployment and repair deployables and pets. While being repaired, the deployable or pet deals increased damage, similar to the Focused Repair Arm.
Alt-Fire extends the repair beam over all nearby deployables and pets, repairing them all as well as increasing their damage. This fire mode consumes a large amount of Power, and the damage boost isn't as strong as the Focused Repair Arm's. But this is very helpful while setting up 3 devices all at once.
A specific epic varient is available for purchase at level 23 from Dome City's Robotics Conquest Gear vendor for 200 Mercenary Tokens. Uncommon, rare, and other epic varients are occasionally awarded for completion of high-end PvP and PvE missions.