You can't remove scratches on blueing. Scratches on blueing implies the blue is no longer there where the scratch is. More scratching (which is what using an abrasive polish is) won't bring it back. Paint is different, there is the thickness of the paint and provided the scratches don't go through the full thickness, you can "cut" the surrounding area so that in effect you reduce the paint thickness to what it is in the depths of the scratch, so the latter is ground out. Which you can only do a very limited number of times, obviously.