Board Thread:Speculation House/@comment-25266931-20151209055514/@comment-4010415-20151213051939

The blade was red. We've seen swords with red blades before.

We've also seen characters use their weapons while using their Semblances before. Prime example: Glynda. Her Semblance is telekinesis, and she always gestures with her crop when she uses it. The best guess there is that she uses her crop to help her focus her Semblance. Weiss also sometimes gestures with Myrtenaster when using glyphs, such as when she pointed Myrtenaster at the big glyph she made to catch Ruby in Players and Pieces, as well as when she swung Myrtenaster through the air right before that glyph launched Ruby.

Some people might simply use their weapons to help them focus and direct their Semblance.

As for the fact that mankind ahs yet to unlock the secret of Dust, that seemed to me to be more of a "They don't know where it comes from or what it's made of" type of thing. There's also the fact that Cortana said they don't know how using it might affect their world (which, curiously, reminds me of Mako energy, which Materia is made of, if I remember correctly, and Monty compared Dust to Materia). Nothing about any of that implies "There must be more powerful, amazing types of Dust they haven't discovered yet!" to me.