Thanks for all the replies guys.
I'm in the Midlands so not near the sea and not aware of any salt water. There was a scabbard but that fell to bits a few years ago.
I've just another look at the blade and the it looks more like surface rust rather than pitting so, maybe, not as bad as it could be.
I'm only a few days in to trying to understand the blade and get a grip in the different names of all the pieces so there's no rush from me to do anything drastic with the blade.
My plan is to see if I can get someone Paul recommends to have a look and go from there.
Hopefully it will be good news but we shall see.
I'll update as I find out more.
🌲🌑🌲