That's what I really enjoy about his "magic", personally. I don't know if it has to do with being an engineer.. or maybe the other way around? But having such practical reasons and even explaining some metals as the body of other gods was great and kept me engaged.

Wondering if the characters had reserves or vials on them or other tricks up their sleeves kept the magic interesting imo.

And I could be wrong, as I've only read the series (all 7) once, but I believe that the mist itself is never fully explained? That filled the traditional role of the "mysterious" origin of the magic. But once again, I may be a bit off here..