Shield is indeed an armor, but in FFXIV it's a weapon. Data wise it is indeed a true class, it's makeup is like any other class, but there can't be a job attached to it unless it's a requirement for another like how Paladin is Gladiator + Marauder.

Getting rid of it is pointless since you could easily say they could get rid of Marauder because they can easily shuffle those abilities to Gladiator and Pugilist. Nothing is really going to happen to this, it's just a secondary set of (helpful) skills you learn through leveling it.