it looks like a leather punch to me, but it has a blade instead of a punch. The nob can be used to rotate the blade 90 degrees. It has some writing around the center, but I cant make out what it says.
I think this goes with your saw blade rack. It's called a saw set. Used to put the set back in the teeth after you sharping it. I have one but its made different
Looks sort of like leather working tool to punch/cut slits in leather edges for lacing. Can't see the blade very well though, and it looks like the anvil is missing.