Also known as: ARX-8, レーバテイン
The upgraded Arm Slave piloted by Sagara Sousuke, making its debut in Full Metal Panic! Invisible Victory. Replacing ARX-7 Arbalest, it incorporates a 165mm Demolition Gun so powerful it can only be fired while using the improved Lambda Driver, and a more conventional "Ponytail" system for the Driver's activation.