An interesting Named Sawback bayo "balloon service" for discussion

[Jumper]

The frog has no marking on it that I can see.

[sb98]

The scabbard was originally issued with a matching combat bayonet (the same maker and serial number would be marked on the blade). It was likely mis-matched with this bayonet by a souvenir hunting vet or anytime in the subsequent years since WWII. The bayonet would not have been in use or worn during WWII if that's what you're thinking.

If you want to get an appropriate scabbard, I’d keep an eye out on ebay for a similar WWI era bayonet with three rivets in the grip. If you’re patient you could probably find one the $100 range, especially if the blade isn’t in great shape. Of course you'll then be breaking up a set and end up with another bayonet without a scabbard, but it could be pretty tough to find a scabbard by itself. Post-WWI dress bayonet scabbards are likely too narrow for the blade to fit (that may be why it ended up in a WWII combat bayonet’s scabbard).