Au Ra Origins: The Dawn & Dusk Theory [Spoilers]

[Cilia]

All of the Spoken - Dragon mating speculation fails to answer a very key question:

How would it work? I mean, physically? There is a massive size difference between dragons (esp. Celestial Wyrms) and a Spoken of any race, and dragons in this setting are not known to be able to shapeshift into Spoken. Spoken can become dragonkin, but that is a one-way trip and they're not dragons per sé, just beings who heavily resemble dragons.

As for Zantetsuken's origin, who knows. Maybe it was a primal in the vein of Alexander. It still leaves a pretty big question open though (the "Norse name" vs. "Eastern-named weapon"), one that's not like to be answered any time soon (if ever).