I mean for starters all the 50 up job quests always end in a caveat from the trainer telling you to go find/learn this skill. Which becomes a requirement to continue the quest later on down the road. Why couldnt this just be the flavor of BLU's manditory skills within the framework, as it would be a normal job. Most class quests make no sense anyway as to how other jobs gain their skills through them anyway. PLD 2.0 job quests had you necromancing dead paladins to kill them and become more palidin-like at some point(?yup checks out) so the format of finding the necessary bread and butter skills as a job quest requirement seems fine for BLU. Since BLU has an actual trainer, like all Jobs/Job quest do, its just because their quests arent the same, come to x locatation, talk to x destination, fight enemy in preplanned purple fog location?(they do also have a few of these types as well, to be fair)