Wind Skills
Crockel was the second smallest empire out of the four empires and it was also regarded as the weakest empire because of its losses during the academy competitions and the general empire competitions.
But being the weakest empire didn't mean the people there lost their rights to the other empires, they still lived their lives normally with their only threat being the demons.
Although they were the weakest empire, Crockel produced very good fighters who went on to join the military-run by the strongest empire Phoenix. Phoenix was in charge of assigning various military personnel to other empires to make sure they had a little protection if a demon attack was to occur.
Sure you could train to be a soldier but without going to Phoenix military academy you could never be recognized as one, that was the reason why some of the students who wanted to join the army would go to Phoenix or they would go there after graduating from their normal academies.