Pretty much - unfortunately the term 'class' is actually misleading. The true name is 'Disciplines', as they're just a set of abilities connected with the use of a specific weapon or tool. Hence the reason why there is no branching within them, because they're not really classes at all - the class names are just titles given to those sets of abilities to make them sound more appealing. Really, the Armoury System could be kind of similar to FFXII where each character was free to equip any weapon type, but they were not given 'class' names.