Classes are divided into broad categories. All Goldsmiths, Alchemists, Culinarians, Weavers, Leatherworkers, and other classes who craft items are called "Disciples of the Hand". The Fisher, Miner, and Botanist classes that obtain items from gathering are called "Disciples of the Land". Battle classes are divided into "Disciples of War" and "Disciples of Magic" depending on their primary attack mode.

You'll never have to worry about picking one of these. They'll be listed on equipment, though, to tell you who can equip it without having to list every class separately.