Shape wise, it reminds me of a tool used for metal bodyworking/panel beating.
Unfortunately I can't recall the proper name, but seem there's a distant memory of "shrinking" being in the name somewhere (or it might have been "stretching")
The idea of the teeth was to make the tool "grip" the metal whilst beating it over a former, so it wouldn't slide off the metal, the offset was in the tool to allow space for your fingers to stand off from the workpiece as you would use the tool to "slap" the workpiece (think forming a curve around say a headlight)
Really can't be sure, but that is where I have seen things of this size used for, I used to be a toolmaker, still posses a LOT of rifler files and they are significantly smaller.
Just an idea
Cheers
Simon