There are lots of things you can try.

- metal polish like Mothers, Maas, Autosol. One caveat: if you have any gold on that blade, don't go anywhere near it with polish as that may destroy it. Looks like there's rust under the scales there. One thing that has worked for me on a couple with situations like that is to try applying metal polish with dental floss that you work in between the blade and the scale. There is of course the option of removing the pin, cleaning the blade thoroughly, and then re-pinning, but that depends on how comfortable you are with such things.

- a pencil: rub over the spots with a regular pencil lead. It can be surprisingly effective

- steel wool