Semblence is hard, since I don't exacly know what it it. But Felix uses a fire-dust infused boardsword that can change to a shotgun, Aqua uses ice dust infused gloves/clothing, similar to Cinder. The other two I haven't figured out yet.
That's alright, I don't really get their concept either. And cool! I'd definitely kill for a one-on-one between Felix and Ruby, they both have their advantages and disadvantages from what I can infer. ^^