[quote=@Crimson Raven]
<Snipped quote by Onarax>

Err...what they are (trying to) say, is that C through A Rank is passable, and S-Rank requires GM permission. There is also X, which is even more powerful, but I don't know Caits preferance, but I don't really recommend it.

For judging basis, if you have seen the anime/read the manga, A-Rank would be about Grey's power level, S-Rank would be about Erza's power level. If you havn't, C would be weak, B strong, A very strong, and S would be super strong.
[/quote]

^ What he said.