Get yourself a heavy guage piece of copper wire the same guage as used in electric company electric lines 4 to 6 inches long. Whatever you feel comfortable working with File the tip on one side until you have a nice sharp edge and remove the surface rust with it. Resharpen if it gets dull, use a file handle for the wire grip.
The copper is softer than the steel but can leave marks if you get to rowdy with it. Then try the semicrome if needed. The rust does leave a stain if it is a large spot. Metal will polish metal. That is how the ancients burnished gold and silver.
Steve

"Insanity is heriditary. You get it from your kids." Quote from Ronald Regans diary.