Buy Amerlene parkerizing from brownells.....bead or sandblast the blade (stainless will not work)....mix the solution according to the instructions (easy...i dont even measure anymore)...heat in a pan over the hotplate or oven burner until the solution comes to just under a boil like 200F....then place the degreased and blasted blade in the pan......try to set it up in a way that the blade doesnt touch pan bottom....like on edge. Wait 5-10 min....rinse in cold water, then some baking soda ....oil and you are done.
If you heat your solution over a burner....just make sure that the blade isnt directly over the burner in the pan...offset it a bit or the blade may turn funny colors.
Another trick is to coat the blade in Cosmoline and bake it at 300f for 1/2 hr and you get a bit of the greenish color like on old WWII rifles.
You can also use cold blueing over the parkerizing if you dont like the color you get....depending on the steel it will range from gray to black.
Hope this helps!