Ship weathering in 1/1200

I think you could still do a few rust stains in areas where larger stains are found, as below hawse holes.  To get very small rust streaks I use the tip of the sharp double ended toothpicks dipped in a shallow puddle of paint.  I can make quite small stains/streaks that way.  Maybe also a chalking of horizontal surfaces with a lightened version of the deck color.

I've modeled quite a few Superior 1/1200  ships over the years but never tried to weather them. I've often thought if I did I would buy the 0000 brushes and make the smallest streaks possible. Or those mini dabbing brushes MicroMark has.

Just remember, the smaller the scale, the more muting of color you need to avoid a "phony" look.

Practice makes perfect as with anything.