Considering jobs will prohibit the use of skills from another class.. Materia

[yukikaze_yanagi]

Players can already equip skills from other classes. Its called the armory system.

Yeah, too bad with jobs you can't.
Personally i'm againt having skills in materia, until they're unique to a job. jobs came out for much an unique fighting stile in opposes to jack-of-all-trades classes, it don't make sense using similar skills with jobs in form of materia (limiting your fighting potential in the meaning)