An air impact wrench doesn’t just work by providing more power in terms of a rotating motion (like an electric drill). Because of their high torque, they would rip your arm out the socket. Instead, a lot of the torque power is delivered via a rotating mass inside the tool. This mass releases its energy in the form of impacts that travel through the bit and into the bolt. That provides more energy to release or tighten bolts and lugs nuts, without hurting those chicken bones you call arms.