Jamie There are several factors that affect how long a tool holds an edge. Hardness is often confused with the toughness of the structure of the steel, which also includes things such as the material going into the steel and the grain alignment. Cryogenics helps align the grain as well as how it's hardened. Very confusing and involved process. The Thompson tools being particle metal can hold more Vanadium than cast steels. That's one of the reasons they hold an edge longer. Doug has them hardened correctly. He did increase the actual hardness to Rockwell 62 which should hold an edge longer. If you get a tool too hard the edge becomes brittle and won't hold up as long. Doug worked on that problem and found he could go that far and not lose any quality. Wish I knew more about m42 but just haven't done the research.