Why change to the Spatha?

[Endre Fodstad]

Yes and no, Robert. They could make decent carbon steel in their bloomeries, but the yield was relatively low; the taller furnaces of the early to high middle ages "solve" this problem primarily by increasing the size of the bloom, and consider also that the japanese Tatara bloomery, from which they refined the steel used for their weapons until the (european) modern period, is not fundamentally different from an european roman or medieval bloomery. Folding helps, of course, but they could get their hands on high-quality steel.