Thanks Jared... I did a very poor job of tying things together, and never really covered the point I was trying to make....

The main point being that I think its a mistake to assume that a 600 year old sword blade is as hard and tough today as it was when new, even if never used. Since not really tempered the same in the modern sense, its not necessarily as stable as something manufactured in the 20th century is likely to be.........

It might be in the same condition, it might not...........

Tying this to the present, if "slack quench" and other ways of heat treating worked well enough 600+ years ago, a sword done with one of these "alternate" methods is liable to be just fine, done correctly. A blade that tests 45 to 48rc should be more than hard enough to make a decent sword blade, everything else being ok..............