Board Thread:Speculation House/@comment-114.79.60.17-20160626164308/@comment-3146930-20160627041335

114.79.62.216 wrote: the dust air bullet seems good, but the control of it's trajectory or movement probably is his semblance,

I agree more with this. I mean we have seen other people use Dust as a type of projectile, like Roman with his cane, Yang with her gauntlets, and that one guy with the trumpet. Mercury is the only one that seems to actually control the Dust he fires, making it spiral around and eventually causes all of them to converge on the same spot. However it is also possible that he is manipulating something within the Dust (like how Pyrrha controls metal) or possibly even air currents to direct his projectiles.