I have a few guesses, at any rate:
- It's sort of five-pointed, which suggests something to do with the philosopher's stone;
- It's got the flamel, which suggests Dante.
My most likely guess, though, is that it's the one used for disabling homunculi. I seem to recall that the circle used to disable Greed had a flamel on it... Not sure though. I'd have to rewatch the episode.
awesomeness by Arakawa, Project FMA banner by Aribelle, avatar by meI draw things.