First and foremost this topic is in the wrong section of the forum, it should either be in 'Combat Discussion' or 'Game Guides'.
To answer your question,
ATK stat = All normal attacks
MAG stat = All skill damage, skill defense
It is most likely intended to be that way. Usually Mystics can 1HKO any class with low MAG with their skill, the only counter for them is debuffs and normal/critical attacks as far as I know.