Wostenholms are pretty common razors. Ive been keeping an eye out for some time for a nice doubly carbonized frameback. The one you have could probably be cleaned up and made into a decent shaver. The best place to start is to get some Maas or other metal polish and see how far you can get with hand polishing. If that doesn't do enough read up on hand sanding. Either way the active rust will have to be removed.