Looks like a pair of crimping & fishing electrician's pliers to me. The piece below the jaws is where you run your metal 'fish' tape and grab it.
I have collected some cool old stuff I actually keep in a living room bookcase. I have a set of triple beam balance reference weights in different sizes (each looks like a miniature keg) and each is set-into a pine wood block with graduated holes drilled into it to hold the weights, a vacuum gauge still in its original packaging, it has all-sorts of gradiations on it to suggest what to check on the engine, when you hook it up-to a vacuum source on the intake side of the engine; a cool die-cast keyhole saw that can position the blade in several configurations for cutting in confined spaces, a wood plumber's level w/a graduated thumbscrew to set it up for different pitches (inclinations) though the standard drain pitch is 1/4" per foot, or 2-1/2" in ten feet. You get the idea, just some stuff that would probably be rusting away in a landfill if I didn't recognize the purity of functional design and choose to display it. Another cool one is a pair of cast-iron star-shaped anchors for a post-tension structural installation. You saw these a lot in buildings constructed early in the 20th century, they were washers which were on the outside of a wall w/a hole in the middle of them, and then a thick structural steel rod would terminate just after the washer, usually w/a nut threaded onto the steel rod. They kept the wall from spreading from the roof load, or the load of the next floor. Francis Brannigan, in his famous book for firefighters, "Building Construction for the Fire Service," warned about how catastrophic collapse could occur due to those anchor/washers failing due-to the progression of a fire, and eventual weakening of the wall section where the post-tension rod made its thru-wall penetration. Brannigan said that if you saw any indication of structural distress in the vicinity of one, it was reason to terminate all interior operations, evacuate all fire personnel, and to move to an exterior attach from an interior attack on the fire. Why? Because the building would soon be collapsing. Ever-see a planned building demo? Each floor from the top-down collapses on the next, called a 'pancake collapse.' Think 9-11-2001.
Yes, a good choice for the man-cave display. I usually will use acetone or mineral spirits to clean something like that before I bring it into the living space, and leave the patina of use it has acquired to be seen. Throwing it into a bead blaster and painting or powder-coating it might make it look 'like-new' but it served many years in your father in-law's toolbox, toolbelt, or workbench, and now should indicate through its appearance, that use.