Honestly I believe relics should involve some sort of grinding.

I mean the obtaining the relic is simply trading in tomes. Upgrading it though it needs a grind.

The biggest hurdle is simply fate farming, which you get guaranteed drops from each fate. You could also go into Bozja and cluster farm and get memories that way as well randomly but that would definitely be way too much grinding. Its a low effort upgrade honestly.

you can do a little bit at a time and make significant progress.