I dont think they stamped blades. Tangs yes - before hardening. If you stamp after hardening the metal, now very brittle, shatters.
Besides, during hardening the steel moves around and deforms a bit in the thin parts - the blade - so it is left a lot thicker to counteract this, then ground to its finished stage before tempering to relieve the stresses. Obviously this would erase any marking.
Anyting on the blade would be acid etched (depth aka bite and colour fully controllable from light fosting to deep relief) or engraved, with the telltale engraving marks showing whether it was hand or machine engraved.
So no chance of upside down characters or mixing font types, just the vagaries of the process involved and the inevitable signs that a human did it on a concave surface, IMO.
Regards,
Neil
PS Voidmonster - still up for hand encoding ocr?! :)