First, give us a glamour catalog. Once you've gotten a piece of gear, it unlocks its glamour via the catalog. Even if it's a limited catalog, that's fine.

Second, make raid gear convertible. The gear will convert into a materia carrying the unique property of the gear. The materia will have unique melding properties -- for example, it can only be melded onto a new type of materia slot. And, when removed, it is not destroyed. You might have to adjust SB rates so that raid content SBs raid gear much faster.

Third, make the materia purchasable and make it cost a sizeable amount of unlocked tomestones (I'm thinking 2000 tomestones for 1 materia). At the same time, keep unlocked tomestones relevant for other uses. Currently, the market for eso mats has exploded because so many people no longer have the eso to spare on them due to purchasing Umbrite. That way, while players playing catch-up with their tomestones are spending it on materia, the players who already have the relevant unique properties via converting old raid gear will be able to cash out in other ways. And, due to the glamour catalog, they will also still have the option to glamour the gear.

New players can catch up with a good amount of effort and content variety.

Old players still get rewarded with glamour and whatever benefits they get from being able to spend their tomestones freely.