Expendable light melee infantry.
Arco-flagellants lope alongside faithful armies in packs, their lashlike limbs whipping back and forth as they follow their priestly masters to battle. When the enemy is sighted, they are driven into a frenzied killing rage by a potent cocktail of adrenal stimulants and neural kill-signals, whereupon they hurl themselves into battle with no thought for self-preservation or restraint. Hacking and slashing with cyber-implanted flails, pneu-mattocks and cleavers, they fight on dementedly until there is nothing left of their foes but a pile of mutilated corpses.