Remember when Roman shot a crystal and it blew the hell out of a building? may want to use come sort of containment vessel and powder-form dust, easier to control and manipulate. as for the semblance absorbing dust... so far we've seen that it is pure energy that ANY aura or semblance can be used in combination with it, so i assume it would be fine for her to use a semblance capable of manifesting in tangible form with elemental energy from dust.
Now, if you'll excuse me, my brain just turned off.