Board Thread:Episode Discussion/@comment-4010415-20170717151617/@comment-26397825-20170719085517

Considering the gravity glyphs have always been used with Myrtenaster in hand(in fact, she's pretty conspicuously used Myrtenaster to make the black gravity glyphs and we know Gravity dust is a thing), it does seem likely that the extra effects are dust-based.

That being said, I doubt it's ice dust. Weiss has always used her Semblance with ice to shape it, and is extremely comfortable doing so. However, she struggles immensely with summoning. For someone so good at shaping ice dust with her Semblance, you'd think she wouldn't have so much trouble with summoning if it was just an application of ice dust to her Semblance.

Personally, I sorta think the summons are tied to steam if anything. They are hazy around the edges and waver like steam does. They appear in clouds of white, which could be either wind or steam. Winter doesn't summon in the fight against Qrow until after she's pulled her second sword out, which we have determined appears to have steam dust in it, and that's the one she stabs into the ground to summon, I believe.

So steam has much more likelihood of being the one tied to summoning if dust is indeed a requirement for it.