Good question. I have heard that gun bluing will not work on stainless...of course stainless used in guns is different than watches and that might make a difference. It just wont hold to the steel.
You might poke around some knife forums with a lot of custom knifemakers...many fittings (not the blades) of customs can be a 300 series stainless and they will be able to tell you how different applied finishes will hold up.