If that "Solingen" is put on the blade with a gold wash (rather that etched _into_ the blade), it's going to come off as soon as you touch it with sandpaper. [I haven't worked on gold-washed razors, but that's what everyone else says.]

If it's actually etched into the blade, you should be able to use fine sandpaper _around_ it to get rid of most of the rust, and metal polish for the rust spot(s) actually within the etched area.

Charles