Board Thread:Speculation House/@comment-24219008-20140408172114/@comment-3146930-20140408184424

I think there are two kinds of Dust. There is Dust, which mankind was born from. Then there is Dust, which mankind named after the thing that gave them life (and the type sold by the SDC). I don't think they are the same as the narrator referred to Dust as "nature's wrath," implying that Dust as seen in the series is mostly used for elemental type attacks.

However the original Dust could be the reason that humans and Faunus have a Semblance, but if we learn later that the Grimm were also born from this  Dust, then that argument sort of breaks down. Good idea and you may be on the right track.