Death Arms is strong...really strong. He is able to lift things that no normal human can lift. His quirk gives him this superhuman strength and in turn his hero name.
His first ability is a free Enhance that gives his attack with a printed five or greater difficulty plus one speed and plus two damage. He can buff up his attacks but only when they are difficulty enough to require his superhuman strength.
Death Arms' final ability is a Response that requires him to destroy a foundation as a cost. It triggers after his Rival's Ready Step and lets him commit two of their foundations. This ability is incredibly powerful since his rival loses those resources for their turn and for Death Arms' next turn!