I quite like this explanation, and withdraw my objection.I'd not gone back and read a lot of the Dwarven culture stuff, but you know, since there's this "once proud, now exiled"-ish vibe going on, would it ruin everything if Rogar USED to be a war god, but after his worshippers failed in war, he--like them--has evolved into a craftsman, using his skill at arms to craft the tools he once used in battle? And like the dwarves themselves, he still holds anger for past glories. He, like a lot of them, wants to get back to the fight, but the time is not yet come.
It might be too complicated, of course, but might likewise explain the axe / forge stuff in a way that likewise reflects the history of the dwarves.
As to the Seithr vs. everyone else stuff, I think you can make that work if you think of the Seithr as a kind of self-contained paradigm. With fewer of the other races there, and built-in resources, the Dwarves in that region did better at maintaining / rebuilding a society, though even they are still a bit at odd ends. Seithr dwarves become a kind of offshoot of general E'n dwarves, whose society is uniquely influenced by their environment.
I think it's fine if Seithr dwarves are different from deep dwarves and other dwarves. Heck, the elves in Jirago and the elves of whatever that forest kingdom is have a have a much larger cultural divide than that.