Some cool ideas. I was thinking of Dust Chakrams a while ago.  Kinda like my characters Deep Magic or Weiss' Myrtenaster, it doesn't have a secondary form. It does have a dust selection system built into it though. Just by pressing the button and flicking the wrist, the user could send a "wheel of dust" within the chakrams spinning. Another press of a button and the wheel stops and infuses the chakram with that selected type of dust. It would work perfect for CQB and you could throw it for good range potential. I never figured out how to return the chakrams after they were thrown though. I mean you could be like Captain America and just bounce it off of other items and have it return to you, but I'm sure there are other better ways to do it too.