Im in total agreement. The cobalt is not as strong as hardened blade steel, period.
My concern for the modified chefs knife design I described in the Custom Knives forum was whether deflection off bone, or nicking bone while butchering an animal, might deform the edge. Cutting the mild steel plate indicated to me that, with care, those kinds of contacts with bone shouldnt be a problem. As David told me, though, the blade on my fixed hunter is not meant to be an ax. The blade is ground very thin to the edge, which is the foundation for its impressive cutting efficiency. But that thin edge on a 40 Rc material, like Davids cobalt, is certainly subject to damage by cutting very harsh materials, or by heavy torquing against hard objects, or by chopping. It has to be treated with respect for what it is--a precision cutting instrument.
As far as the folder goes, to me the concept of a strong folder is an oxymoron. I take care not to stress a folder if I can, because theyre inherently subject to damage from stress. Obviously, some folders are stronger than others. That said, a serrated cobalt blade on a folder is a good choice for me, because to cut rope, cardboard, open packages, and zip through seatbelt material in an emergency, its very efficient. And in a humid, rust-prone environment like coastal South Texas, its also very durable from a corrosion standpoint.
Davids lock-back designs and synthetic handle materials are also very rugged for the weight--light, efficient cutters, reasonably priced, that wont rust and will stand up to most long-term use very well.
Whenever I go hiking or back-packing, or hunting in remote mountain areas such as the Rockies, I always have a Busse Basic #5 in my pack, because in a survival situation I might need a tool that I can count on to stand between me and anything nature can bring. Whenever Im in my vehicle, I have a Busse or two under the seat. They do yeoman service for me all the time against heavy, tough stuff that needs be cut.
But short of that, a one-hand-opening folder in my back pocket for EDC and a very fine-edge fixed blade knife for my hunting needs--mainly butchering game animals taken on South Texas ranches--fill my needs very well. Oh, and a good machete and stainless filet knife!