I have followed this thread with interest and found the metallury comments informative. However, I feel from my limited knowledge on the subject that a 'Occam's Razor' approach may be relavent (not sure if the 'Razor' is wootz...but I digress
).
In my mind there are so many variables to this debate...the quality of the steel, the differences of forging technigue and method, the design and thickness of the blade, edge formation (hollow ground, flat ground and so on)etc etc.....that it would be almost impossible to reach a conclusive answer.
But I know this to be true.....an old, battle weary sword MUST be a GOOD sword......It has survived all the testing it required, perhaps this is why they end up as 'heirloom' pieces.......'here son ..inherit my sword...which I know to be battle worthy and will not fail you in combat.'
Simplistic...I know.....but then again simplicity served 'Occam' well
