thinking about uniqueness in compare to other Final Fantasy games. jobs had a unique abilities that is class only, also in FFxi there was some passive abilities that was class only and some that carried over when you sub-job.
FFxiv doesnt have any class only passives and there isnt any unique class only active abilities either. there is a need for passive class only abilities that grow with rank and the passive abilities gained through marks would have a training type quest line that may show how to properly use "heavy..." skill or how to convert mnd to dex, while adding some lore. but what is also lacking is class only active abilities similar to FFxi's 2hour abilities. i would like to see some class only abilities maybe one 1hour & also one or two 30 min timers. good example of some passive class only abilities would be:
gladiator = physical def up / base damage up
marauder = parry up / ?????
pugilist = evasion up / attack rate up
lancer = parry up / critical rate up
archer = evasion up / physical accuracy up
conjurer = magic def up / magic potency
thaumaturge = magic resistance / magic critical rate
i you noticed i used 1 defense passive and 1 offensive passive but other types of passives could also be like MP regen, increase max magic or physical damage, treasure hunter (thief), etc...
name changes could be a more generic naming standard thus saving classic names for a more prestige harder to claim classes.
Gladiator = Squire/Soldier/Knight (any of these are fine)
Marauder = Fighter
Pugilist = Brawler (new to any FF series)
Lancer = Lancer (still a good generic name)
Archer = Archer (still a good generic name)
while magic classes are harder to give generic names to because most FF series white & black mage was the lowest form of magic user with the exception to FF tactic's chemist which evolved into white & black mage.
so thinking about what system will easily fit into the current system with minor tweaking. with the current classes not one class has all the skills needed to be a classic job. a good example would be thief, you would need trick attack from lancer, sneak attack from pugilist and flee from archer. keep in mind they did lower the SP needed for 1-30, so ranks 20-30 would be ideal to having multiple classes needed as a pre-req to access a quest line to unlock an advance job. this system would be similar to FF tactic's job system & FFxi's quest line.
leveling/ranking is normal in any MMO and only asking to unlock advance jobs at rank50 with out any other challenges would be to easy and the value of the achievement would drop. yes this system of combination of FF tactics and FFxi would take longer and harder to achieve but this system will still keep the flexibility of crossing skills over while retaining the value of having unlocked an advance job. saying you have reached max rank on an advance job would just increase that value even higher.
Weapons
personally i would also like to see some flexibility with weapons. i think either all classes should have a 2-handed weapon, 1-handed weapon and access to sub classes like shields/dual wield or break the the weapons away from classes, so classes have a more variety of choice to choose from. maybe i want to use a 2-handed boardsword as a paladin or maybe as a dark knight. it isnt that i just want to be able to mix & match skills but maybe i want to be able to mix & match weapons with other classes. sure artifact (tier) gear can favor 1 or 2 weapon to a class but non-artifact can be used more loosely among the classes.