Cordless tools been around a long time, though description has new connotation. Now batteries are commonplace, for centuries such tools ran on calories.
Here's one that I've had a long time, probably a garage sale find. Never seen another . But with little creativity it can be replicated. The best use is on automotive lug nuts. The function combines a free-spinning body when holding the bicycle-type grip, and torque tool utilizing the impact bar. Actuation is by gripping the handle and swinging the arm so lever directs power to the body and socket.
I suppose resulting power could be calculated, but it'll loosen those tightened by a pneumatic...When additional torque is needed just grab and rotate left or right by the end weights.
Click on the picture to enlarge view and read inserted text.
Any questions? Fire away, I'll be happy to respond.