Interesting tool. As I've worked with hot stuff, I can say it has a blacksmith shop background due to the long handles, required when working at the forge. Also the handles look hand worked, not machine made. Another bit of terminology here is the handles were called reins, as horses were controlled with reins, not handles. The head definitely looks like one made to handle a rivet or bolt, a carriage bolt? If I were to make a carriage bolt, this would hold it securely, to move it to a die for threading? For more work done to the shank? I'm guessing a special use tool made for a particular job that we might discern in the future.