So this has been talked about a few times, but the threads where the discussion is featured are quite scattered.
The general idea that you make your jobs Ultimate Armor (Crystal attire set). You do this by obtaining your job's respective reforged Artifact, Relic, and Empyrean armor +1 pieces. You need the 119 +1 piece for each armor, 109 pieces do not work. So in order to obtain the Crystal Ninja body armor, you need all 3 of your reforged body armor pieces. Also you would need to be able to equip S2 items (100 JP's is not difficult by any means).
How the process is completed would probably end up being synergy, but I would prefer it to be a quest. And by quest, I don't mean obtain 1,000 plutons. I mean do actual quests, similar to the original AF quests. Each quest would probably have a single, reasonably easy to obtain item required (maybe Limbus items? I realize they would need to add items for GEO and RUN).
The second part of each quest would be to prove you are a superior <insert job here>. This would be different for each job: for example, maybe a WHM would have to prove their value by healing or casting raise, something WHM related. DD's would have the typical "kill X number of enemies" or certain NMs. All of these tasks should be required to be done solo (no trusts or outside help). If you're interested in this idea, please add your ideas for this section below, or make any other comments about the topic you have.
After you finish that portion of the quest, you go back to permanently converge your armor pieces into one. The quest only needs to be done once for all five pieces of armor. The process is done by the NPC that you first did your original AF quest for.
Once you have all of your armor and are officially a "Master" at your job (2100 JP's) you can begin a second quest to augment the armor pieces. In order for the augments to have effect, you would required you to have it all equipped at once, similar to the empyrean+2 sets. Having the entire set equipped as a Master would enable you to do something fantastic. Example: the BLM set allows you to cast Ultima, or perhaps enhances meteor. The augments would have a unique spell, weaponskill, or ability. Please keep in mind these are just ideas, and you are free to add any input that you may have.