It's a double edged sword though. Example DRG. Ryunohige or GTF Home. If you make something that good, it should be hard to get. If you make it too hard, you antiquate a job. While DRG's problems stem from Piercing being horrible against a couple of key enemy types, such as Undead, it's still disgustingly powerful when geared to the teeth and played by someone who understands the job. IMHO DRG is awesome and fun, but it lacks that alliance appeal that WAR, DRK, and MNK do. It's still probably the most destructive job in the game, but it has enough draw backs that people prefer a less specialized job.

I think JS gear is a really good idea, because it can easily be balanced....because it's only for 1 job. But it requires the Dev team to accurately capture the important elements of the job and highlight them. The lvl 89 JS weapons are a very good example of this kind of work. Most people are aware of several of these weapons, because they were so dynamic-ly powerful that they were the go-to weapon for people that didn't have empys or relics. The biggest draw back is that when you have to move past these kinds of equipment, if you do (obviously BB has gone nowhere....), then you create a lull which makes progress deceptively hard to evaluate.

My preferred idea for how to overcome that kind of lull, is to allow players to keep their unique toys, even if they move past them. Clearly a Widow Maker is not the best G. Axe, but who wouldn't want to keep the unique affect of increasing their double attack damage permanently? Even though you have to give up your toy, you'll be able to pick it up later and enjoy it's job specific goodness.

There are 2 simple ways to accomplish this. The first is to make those kinds of effects from JS equipment such as the lvl 89 weapons into quested job traits. The second would be to include it as an upgrade to Mythic weapons. Both solutions are potentially very punishing, because you can make the requirements very extreme. In the case of having to acquire a Mythic to begin with is an extremely large task, but considering the current state of Mythics, it wouldn't hurt to give them a boost.

I mentioned Mythics because once again they are Job Specific and every job only has 1. Most Empy and Relics have shared custody by jobs and very few people would be willing to create another of the same prestige weapon just because they wanted to get the most out of it for 2 different jobs. In fact the point of those weapons is that you can use them on multiple jobs and they are still very useful.