All spellcasting uses something as a focus to help the user channel aether. Thumaturges and Black Mages use bone and stones (meteorite, gemstones). Conjurers and White Mages use wood. Arcanists, Scholars and Summoners use ink that conducts aether. Red Mages use their well, focus, which usually looks to be made of some type of stone usually. This is why most mage staffs look like they do.

This doesn't just stop with mages though. All the jobs focus and channel aether in some way. Ninjas channel aether with their mudras, Monks with their bodies, Archers/Bards with their songs, Machinets convert their aether into power for their gun, etc. The way they focus and channel aether varies a lot. The fact that all the jobs use aether is why they can all be effective against magitek and the like.