Reviewing your pictures. You appear to have area around the pits taken to shiny "bright", but within the pits is still dark - I suspect that you still have rust in the bottom of the pits. That is what is so insidious about dealing with pits - the rust is down in there! I think you will find that rust is some Fe (iron) atoms from the parent material, combining with O (oxygen). Red rust - FeO2 - has larger volume than parent, so "erupts", creating pits, if let work long enough. Bluing, as I understand it, is another form of "rust" - aka magnetite - Fe3O4 - or very similar - it has very similar volume to parent, so does not pit - old school "bluing" was allowing red rust to occur, then turning some of it into magnetite by boiling, then carding off anything loose and repeating. It becomes a matrix to hold oils, etc. to prevent parent material from rusting further. So want to isolate that parent material from oxygen / moisture - so rusting does not continue - not a "fix", just preventing it from getting worse. Grit blasting, drilling, filing are all ways to remove the rust damage (the "pits") but usually require re-filling with matching material, then refinish, etc.