I think an alternative way to get the relic weapon would be possible, similar to how people these days use Eureka opposed to running roulettes for tomes. At the very least it will give people options, and let you shake it up a bit while you're grinding. Kind of like how a lot of people, instead of grinding ARF for forever, got into hunts.
Then they can frame it like "The House will be more than happy to provide you with the materials Gerolt needs, Adventurer... but if you for some reason find our reasonable prices to be out of your reach, you can always test yourself and go get the materials yourself..." cue the new Eureka area.
What it does mean however that it will be limited more to Diadem-likeness which actually I'm pretty ok with. Because part of the major flaw of Eureka is having to progress, only to reset constantly. Having the one zone in it means any progress made is kept upon future revisits.