Pitting will be your enemy as they will be deepest in the blade. The blades are usually rattail tang peened over at the butt of handle. I would remove the handle from the blade and start there if you can figure it out. Take your time. Wet/dry sandpaper and block to keep the lines starting at the lowest you feel comfortable then work your way up once you get it cleaned. I wouldn't worry about the deep pits, you may ruin the blade contours trying to get them out. Leave it for character.
Alternately you could use a rust solvent but they can go deeper making pits harder to clean up.
If you cannot get the blade and handle separated, you won't know how bad the rust is under the handle. It could fail at a bad time on you. Pointy/sharp/heavy thing flying around like a boomerang with edges. Not good.
Good luck, sir.
