WAR and GNB are allowed to have some of their core abilities as early as ARR, don't see why PLD and DRK can't get the same treatment with early Holy Spirit and BloodSpiller
Sheltron could use a duration buff too alongside the added regen, 4 seconds of mitigation isn't a whole lot when compared to Camouflage and Dark Mind

(why is Camo a lv 6 skill anyway? what do we gotta do to get Dark Mind and Bulwark that early??)