Board Thread:General Discussion/@comment-165.234.190.56-20141102075433/@comment-68.49.230.229-20141102092938

Probably for Pyrrha is that any metals treated or mixed with dust would also trigger under the influence of her aura through her semblance's connection. And Yang is more internal and channeled somewhat through her hair (more likely as a visual indicator of it active like her red eyes) if anything, the dust would likely needed to be woven into her clothes or on those she's holding onto during activation.

So you'd either get:

Flying blocks of solid ice with a metal core

Or

A raging beserker in ice armor, that's on fire

(Possibly an ice sculptor that doubles as a light)