Currently at least on my server there are many end game dungeon runners sitting on millions and millions of gil that all they spend it on is repairs and food. There are also crafters who only way of income is selling said food and starter endgame gear and furniture. I think a good way to not only give the dungeon runners more reason to log in between weekly resets and give crafters something to help out at the high end of end game. Would be to give them the option of crafting augmented versions of the endgame raid gear.
As a example someone with a High Allagan Torso piece would need to spirit bond the armor to 100% and also obtain some rare materials from various places (example trials or other dungeons) Once obtained they find a Crafter with the right class for there item and high enough craftsmanship and control to then upgrade there item similarly to the meld system with a chance that failing not only can destroy some of the extra items but mabe remove a few% of the spiritbond if it fails. Another option would be to make the best gear in the game crafted from Unique untradeable drops obtained by desynthing gear obtained from the high end game raids the new crafted gear would then be unique untradeable as well so only the person crafting it could were it. I personaly belive the first option i gave would work better for the comunity as a whole.
Also to expand upon my first post the augmentations could instead of being static augmentations such as stat boots they could boost specific abilitys. Example if a Bard has there High allagan piece upgraded with some Dematiria from a ifrit weapon then it would make there flame arrow aoe more potent. Or if a Paladin augmented some dematiria from a titan weapon it would increase the defensive abilitys of shield oath or Bulwark. for a whm a Garuda or leviathan dematiria may augment healing abilitys or the damage done by Aero or Aero 2.