Quote Originally Posted by StouterTaru View Post
No base class means it doesn't level up a class as it levels up, not that classes/jobs aren't required to unlock it. You need archer to 15 to unlock BLM, but archer isn't a base class for BLM.
No Soul Crystal and no Base Job likely means you walk in and the NPC goes "Hey Wanna be a dark knight!" and you go "SURE!" then they go "Righteous, here's your great sword and your first job skill, now go pwn some noobs and come back in five levels".

By the point you pick them up you should have a shit tone of job skills from just leveling your main's cross skills.