From the WTS sub forum, a German cutlass is offered with this
description:
Rare WWI U-boat cutlass
100% original German Model 1911, Marine sidearm or SG1911 cutlass. These were only made by Simpson & Co. It’s Crown M on the spine. The scabbard is not original to the cutlass, but is period made from Belgium sword scabbard and fits great. Very rare only issued to U-boat crews. This one is NOT unit marked.
Why would such a boarding cutlass be issued "only" to U Boat crews?