You could cold blue it or there is a recipe around here somewhere to put motor oil on it and heat, then wipe it off to achieve a dull gray finish. I'd just wear it in by using it..Geo
SKB is on the right path. Anything with a bit of corrosive acid will tone down the polish and it will be permanent. I just apply a bit of nitric acid, wait a few seconds and then wipe off. Neutralize with baking soda.
A mixture of Hydrogen Peroxide to provide the Oxygen and any Acid you want to use, I prefer Hydrochloric Acid but white Vinegar will also work, dont be in a hurry just use a moistened cloth to apply.