Could it be a variant on a saw set?

 

Or maybe a hand held edge beading tool for sheet metal.

I was thinking wire tensioner/twister for fencing but that's a WAG.

im with lawnjockey on this looks like something to put a round edge onto sheet

 

I'd like to see more pictures. Full tool and both sides if available. I agree that it looks like it could be something to roll the edge of sheet metal but I'm not sold on that. as you'd have to have a vertical bend already. Maybe a barrel sealer? something to roll the end of a barrel lid over to seal it permanently?

It's a rorschach test for blacksmiths...