I think you could bring it a long way back by hitting the surface with some wd40 and light sanding to remove the surface rust. You could also go over it with a soft wire brush or drill attachment if there is rust inside the etching. I’m not sure how much more rehab it might need after that, other than a resharpening to restore the edge.
I’d be careful with chemical treatments unless you know how the finish will react. I have very little experience with them, so perhaps someone more knowledgeable will have better advice there.
Good luck!