Big bill, no prob. My pleasure.
I work in the boiler industry(small to medium scale industrial) and rust is something I deal with constantly. Before that I was in the pre-stressed concrete industry and rust was a primary threat there too. If anyone wants to do some research on rust, the US navy is the place to find the most info. NOBODY IN THE WORLD knows more about rust than the US navy. It turns out that rust really is contagious. There are micro-organisms that live on metalic surfaces and within oxides of metals that secrete enzymes that promote rust. These micro-organisms can be a serious problem inside boiler systems...and also on the exterior of the navy's iron based hulled ships.
I'm not completely sold on the use of stainless in knives and guns.
Carbon steel is superior in every way except oxidation and some very specific high temp characteristics. Stainless doesn't "flow" at high temp. This makes it impossible to flame cut stainless steel with an acetylene torch...and is probably related to why stainless barrels on rifles are resistant to throat erosion. But in exchange for that erosion/flow resistance, you get a material that is more prone to cracking and crumbling when subjected to long term rapid temp fluctuations. Also, stainless sometimes seems to be more suscepable to damage from prolonged exposure to caustics than is carbon steel, imo. Also, stainless ususally feels soft when you smack it with a ball peen hammer or gouge it with a hammer and chisel. Stainless guns seem to scratch easier and lose their sharp edges faster from holster wear than a blued steel gun or a nickel plated gun does. But paradoxically, stainless is harder to cut with a saw, or to drill, or to mill. And in my opinion, it is also harder to sharpen.
I don't know for sure, but my own personal experience with knives over the years tells me that carbon steel will produce a superior cutting edge over stainless when sharpened with ordinary primitive tools...ie a grinding stone or a very fine file. I used to experiment with sharpening techniques when I was younger.
My conclusion was that the most efficient way to get a razor like edge was to start with a german made carbon steel blade(that rusts vigorously and look for a "solingen" mark) and sharpen it the best you can with a very fine file. Then switch to wet/dry sandpaper(a new sheet) of medium-fine coarseness and without any lubricant that is mounted to a piece of window pane. Then switch to a worn piece of well oiled wet/dry very fine sandpaper that is mounted to a small piece of board with a thin piece of felt between the sandpaper and the board. Then finally switch to a well used oily piece of leather that is covered with fine metalic dust infused greasy crud. Use one side of the leather first, then the other side last. I don't remember which now. But I think it was the suede side first, then the hard smooth side last.
One other thing that is quite odd about knife edges...a freshly sharpened edge is not as sharp as one that was sharpened a week ago and set aside and not used at all. I think it has something to do with the "patina" that develops on the edge over time.
And finally...the sharpest edge known to man? You know what that is? It is a freshly made flint edge. THat's right! Thousands of years of evolution and the stone age man still has us beat! BTW, a freshly chipped or broken piece of ordinary glass is equal to flint in sharpness. So if you want a superior weapon when someone confronts you with a switchblade knife...just empty your beer bottle, flip it upside down, and smash the bottom off of it.
But of course, when you do so, you are sacrificing toughness(the technical term used to describe blade characteristics, not your own personal combat characteristics) for sharpness.