The question to ask yourself is whether this is about the weapon itself, or about the associated content.

ARR had some fantastic weapon designs and some truly iconic name references. It's unlikely that we'll ever see that again, simply because of the increasing number of jobs with each expansion. Final Fantasy lore doesn't have hundreds of iconic weapon names to give out. It's unfortunate, because I would have loved to see an equipable Save the Queen greatsword utilizing a classical, symmetric design and the Ragnarok Zeta glow effect.

At the end of the day, though, the weapons themselves just come down to being fun glamours, and there are lots of alternative ways for players to at least get close to BiS months before they drop.

I think the more important question to ask is the type of content that you ought to attach to the relic. Ideally, players should feel like progressing towards completion of their relic takes them through new content. ARR started out strong in this regard, by having you complete the HM Primals to get to your first step. But outside of that, both ARR and HW very much stuck to having you grind out old content, at which point you might as well just be collecting tomestones like we are now.

Where Stormblood and Shadowbringers excelled was in creating unique zones for the relic. I think Eureka was a bit more ambitious, had more varied zones, and did a better job of creating a sense of overworld danger and exploration. Bozja was more streamlined and more forgiving, but had some really great innovation with the duel system. Both had some phenomenal group content, between Baldesion Arsenal and Delubrum Reginae Savage, both of which have multiple weekly runs even still from their own dedicated communities, much like all the Deep Dungeon content does. I feel like if you want to create a good exploratory zone and good relics, those are the people whose opinions should be sought first and foremost.

But the biggest thing is - they need to start it rolling early, by which I mean shortly after expansion launch. It doesn't matter if the weapon is completely redundant. I don't think the weapon 'progression' matters nearly as much as simply having access to a large zone filled with players to explore together and discover its secrets. In a way what you're really emulating is that older style of MMO where you have to be a bit more patient and rely on a sense of community.