Classes are separated from type 1 to type 4.
Type one classes are simple classes ranging from swordsman to spearman.
Type 2 classes are more advanced forms of classes like magic swordsman or berserker.
Type 3 classes are classes that start to involve elements or drafts, an example would be flame magician, water spearman, etc.
Type 4 classes are classes forged from the very foundation of concepts, a pretty big leap.
I won't be telling you any type for classes other than the only one that you've seen if you read the current 8 chapters : The Author class.