Impact wrenches (all types: pneumatic, manual, electric) WORK.

They are safer than leverage when it comes to loosening nuts/bolts. OTOH
than can easily over-tighten.

In the "bad old days" the professionals used a "Cross" wrench. This always
seemed to work a lot better than the wrench than was provided by the
manufacturer.

Why?

Because the "cross wrench" worked a little like an impact wrench!

Impact wrenches are very good at breaking loose a nut/bolt. Once a
nut/bold is loose the pneumatic are very effective at spinning a nut/bolt
off. A manual impact wrench acts like any other wrench. An electric
impact wrench is likely to be on the slow side until the nut/bolt is quite
loose.