Of course, it is aviation-related.

Stamped "Swallow Airplane Co., Wichita Kansas". It has a cupped plate wrapped partway around the handle that is hinged so that it can swing out and provide more leverage (I guess). He got it from an elderly neighbor whose son was in the Air Force, and that's all he knows.
I did a litle research, and discovered that Swallow (which I'd never heard of) was not merely one of the many little aircraft shops that popped up like mushrooms in Kansas during the 20s... its founders included the likes of Matty Laird, Lloyd Stearman and Walter Beech, and Clyde Cessna was involved at one point. Formed officially in 1923, but I have yet to find out when it folded or was bought out.
No info yet on this tool... I'm guessing due to its very unusual aluminum composition that it was meant to stow somewhere on an airplane for field service... anybody ever heard of this type of screwdriver?