It's an old wallpapering tool for perforating corners so the heavier vinyl types will crease neatly and "sit" into the corner, taking away that "rounded" look.
The modern version is smaller and looks nore like a pizza cutter.
Are you sure? This seems the most logical application so far, and I've asked and shown everyone I know. The head is made of cast iron and is 'diamond' shaped without a 90-degree side to go flush into a corner.