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!

Thanks y’all, appreciate your responses. Will test your recommendations and see how it plays out.

I’ve had good luck with Brasso and an old piece of t-shirt. A bit less abrasive than sandpaper, but it should still be able to remove the rust. The blade print will not be unscathed. My douk-douk was definitely prettier before I started mistreating it. Rinse it off when you’re done, oil up the blade, move on.

probably the spring too did rust :/

if the dark gray patina doesn’t disturb you, put it in diluted vinegar for half a day and wash/dry it afterwards. I plastic wrap the handle as the patina on the spring and the blade messes up the close/open where the spring pushes into the blade (especially the blade corners :/

copper / brass brosses are softer than steel so they are helpful with the blade and the fold handle + spring

i wouldn’t use wd40 on a knife i use for food prep

you can always use a sandpaper if you don’t care about the print on the blade

i love douks but they’re not practical :/

Bring it to be sharpened and they will likely clean it for you.