Job trainers could hand out future relic weapons + story
It would fit since each weapon is not shared by other jobs.
Rather than "toughening" up weapons by doing dgns we already have completed, they could be solo duties and quests, each with their own storyline.
For example, SCHs could have a story centered around Nymian artifacts and once gathered through a series of hardships, meld together for a new weapon.
NIN could be about trying to steal a special scroll from a particular rogue faction that can summon a legendary weapon.
I have more in mind but I'd be here all day. Point is, while its too late for the current system to change this, perharps SE can reconsider the approach at relic hunting to mesh better with thia story driven game.