I remember back as a student in the 1980's I managed to plasma harden some steel with RF and some low pressure hydrogen and another couple of gases (with others.)
I am wondering why I can't buy plasma hardened razor blades since I'm fed up changing my razor blade every 4 days, and want something to last a month.
Possibly the idea is that you keep buying blades, but I'm willing to pay more for something which lasts longer.