The New Class/Job system in a nutshell!

[Sorro]

I sorta believe it will be like classes can branch out into different jobs after a certain lvl that are exclusive of that class, but might use their own arms.

i.e. (used "lvl 40+" for the heck of it could be any lvl)

Marauder---> Warrior (lvl 40+ Axe Marauder)
|
--> Dark Knight (lvl 40+ Scythe Marauder)

Conjurer--->Whm (lvl 40+ 1-handed Conjurer)
|
-->Summoner (lvl 40+ 2-handed Conjurer)

And perhaps the "specialization" will lvl up independently from the core class it derives from, kind of like how the "Physical Lvl" / "Class Rank" worked before that remake of the combat system.