I have one of those and I can tell you they are pretty rare. I have only ever seen the one I have. It is a German Artillery hanger. Mine is maked to the 12th Regiment of Artillery. The blade is very thick on the spine and is a flat grind to the edge. It is surprisingly well balanced. When I had my Inn in England, it was the weapon I grabbed if I heard noises outside. There should be acceptance stamps on the spine right near the crossguard. The throat of the scabbard also has markings and the issue number should match the issue number on the blade. If it does, then it usually signifies that it was taken from someone that no longer needed it, or the owner was a POW. If the numbers don't match, they have been stored and then the government disposed of them.
The makers mark on yours looks like 'FR' which is Frister and Rossman. They made sewing machines in peace time and still do.
The brass will polish up nicely, but leave the patina on the blade.