If you opened the handles to the point that the outside studs is engaged in the half round holes could you get a wire placed in it to align from one side to the other. Then I could see how it could be used to take slack out of a wire.
Thanks for the replies. Unfortunately I can't get my hands on the tool, it belongs to someone some distance from me, else I would test it. It may be a fence tensioner but one wonders how long the strand of wire will remain tense...especially if one owns cattle . Perhaps more a rod bender as Greybreard suggested, maybe a tool made to make a specific design...can't find anything like it on the internet.