I've always liked the idea of opening up full access to the spells known for a BLU, but only allow the stat changes and job traits of spells set, as a high level (lv. 99 perhaps, "Group 3" Merit) ability. That idea has a viable implementation, and from what I saw in this very thread, I'm not the only one who thought of this (the immediate response apparently didn't read the post, as they ignored the fact that the original person that put forth the idea even mentioned the exact same thing I just said).

A 10-20 minute JA that gives you access to one spell you haven't set, honestly, isn't that much of an attractive idea. If it's a spell you found out you actually need, then it'd be set. If it's a spell that's only situational (to the point it's not viable to set it), but still needed enough to warrant said 10-20 minute JA, then you're going to need it more than once every 10-20 minutes, but not enough to justify dropping another, more important spell, to put it in your spell list. Even moreso if you're already in battle, that cooldown isn't something that's gonna be conducive to you continuing to live. I'd say, if such a JA were to exist, 1-3 minutes, 5 minutes at the most, would be the recast, nothing more, or you're just wasting people's time.

Yes, you have full access to all spells, but not the stat adjustments or Job Traits unless you actually set spells for them specifically. You'd still have to gear for each spell like always, for those of you naysayers that will immediately cry "GAME BALANCE" like it has any meaning by this point, and BLU magic has never been anything so overpowering that it put other jobs out of, well, a job. I still don't see whole Linkshells dedicated to just BLUs because its magic is broken or anything. Opening up the full spell list won't change that, just gives BLU more options to handle situations, and doesn't take away from any other job.

As far as Azure Lore is concerned, yes, I agree, it's a pretty lackluster JA that you actually have to plan for, as you only really get any real use out of it via Chain Affinity. Perhaps give it the same JA reset that Spirit Surge does for Jumps, or change AL to give ALL Blue Magic cast under it the full CA/BA bonuses and effects while it's up. Or, better yet, do something that hasn't been implemented yet in this game:

Azure Lore: While in effect, MAXIMIZES the variable, numeric effects of Blue Magic (damage, duration, accuracy, TP effects, etc.), based on the calculations via your stats and gear, that is possible for each cast.

For example, say, with your gear and atmas and stats (ALL IMAGINARY NUMBERS, MIND YOU), Q. Continuum could do upwards of about, say, 5000 damage max, but your actual range is somewhere in the 3000-3500 range, with some spikes near to 4-5k. Under this new Azure Lore, every cast you make of QC under the duration is guaranteed that 5000 max your gear and the current calculations say you're capable of. The same duration of the current Azure Lore now becomes the "oh-shit!" button BLU needs it to be, and gives BLU something semi-unique to bring to the table: guaranteed maximized damage output, utilizing the full extent of each spell. That sets it apart from Black Mage's 0 mp cost, Red Mage's vastly reduced cast/recast times, and Scholar's free use of Strategems combined with increased access to opposing school magics (contrary to what some here might believe, Tabula Rasa *isn't* only about giving Scholar access to both White and Black Magic at the same time).