You have to remember that high carbon steel was a rarity a couple of hundred years ago. Even knives forged from old files often were heated so many times much of the carbon was lost.
Where did you get that from? Trade knives were about 80 points carbon, I think, roughly equivalent to modern 1080, and I've never had much problem with decarbonization using charcoal as forge fodder. I do tend to follow the forge thick, grind thin school of thought, though.
