The saw blade is from my large circular metal saw. (One of my other hobbies is welding). I cut it out with my angle grinder. I did some sharpening on it tonight and it seems to take an edge pretty well but then what do I know?
I sharpened a GI folding knife when I was in the Air Force loooong ago. I stropped it on my leather boot, then on a piece of glass. I could shave the hair off my arm with it. I was cutting a seal off a hydraulic fitting and unfortunately almost cut my finger tip off. I gave the knife to someone I didn't like much.
I don't know much about annealing or hardening so, I'll be doing a google search or I'll search this site as well. I'm a retired pilot, so I've got lots of time on my hands.
Cheers, Elliot