I first looked at this days ago; I didn't know then and I don't know now.
My first thought was, a 'coin/token slot',
mainly because of the offset of the 'features' on the reverse side.
My second thought , it does show properties of a leather strap-sliding thingamebob
is there a piece missing from the middle?
Mike
Do you know what kind of metal it is ?
Although it resembles the Tsuba on a Japanese Katana or samurai sword. The hole in the middle is not tapered in a triangular shape to match the shape of a sword blade as in all Tsuba or hilt plates I have seen.