Generally when I've a bit of rust on a weapon a little WD40 and 0000 steel wool will remove the rust and leave as much of the blue as is possible. To touch up any weapon the best cold blue I've used is OxphoBlue from Brownells. I much prefer the liquid to the paste. It seems to work so much better and it's supposedly the same formula?? It will allow bluing thru a bit of oil so preferation is much less tesious and time consuming. Several coats are usually required to get and nice even coverage.. the steel fur and WD40 are used to scrub the rust loose. It is then wiped off. A couple of goes may be required may be required..depends of the depth of the rust.
