Board Thread:Speculation House/@comment-10380701-20131018004029/@comment-4830106-20131021190444

So i think I got it:

Aura is an external projection of an organism's soul--in the form of raw energy shielding (or power, perhaps).

Semblance is an individual attribute through which Aura can be focused.

Dust is the component necessary for "magic": the energy comes from Aura but is given form and lethality by dust.