I was also thinking that the through hardened mihgt be 57 Rc and the differentially tempered blade might be 59 Rc on the edge and 57 Rc on the spine. So in making the entire knife 57 Rc you are gaining tensile strength but losing some edge retention whereas you get the best of bost worlds with the differential treat. I think a better sacrifice for a small blade would be to bump it up to the 59 Rc where it has its greatest edge retention and sacrifice some tensile strength.