[ossiblue]

I'm going in another direction. It could be an installation tool for brass grommets in shoes/leather, or something of the kind. I think I notice a slot on the inside of the fixed part of the jaw, and that's where the wide part of the grommet would fit. The pin on the jaw would engage into the narrow hollow of the grommet and when the tool is placed with the fixed part and the "hammer" end on a surface, then rocked backward, the pin would enter and expand the narrow end of the grommet.