How do you rustproof and darken a knife blade?

[knifemaker]

I use GunKote on my tactical knives made from 0-1 carbon steel. You can get it in a spray can from Brownells and I would get the dark gray. It will come out a flat non reflective gray black after baking at 300 degrees for 30 minutes. It is very good at abrasion resistant. I make my tactical knives to have removable handle scales. After several years of hard use, remove handle scales and sand down the old finish and recoat and bake and you have a new looking knife.
They recommend sand blasting the steel, but no need to do that as a 220 grit finish will work fine for the GunKote.