"impact driver,"

For those of you who may be visualizing a regular air impact gun....

I am pretty sure he is thinking about a Hand Impact Driver.... the saviour of motorcycle mechanics...

This is a hunk of steel about 7 inches long and and inch and a half in diamter... it can be set to twist either way.... to get things loose or tighten them....

ITS GREAT POINT is that it provides forward pressure at the same instant that it does the turning.... so things like stuck phillips head screws ( the phillips head was actually designed to limit the torque which could be applied ) can be gotten out... BAM your problem is solved.