If you want ideas for Lovecraft stuff here's some links.

Keep in mind that while the Deep Ones are the second* oldest beings in existence, most narratives are focused in the 1800s. When Lovecraft was alive. Civilizations that worship Elder Ones tend to collapse as their relics often drive their holders to madness. Might even have possessed be a requirement to get the most out of a relic's use.

https://lovecraft.fandom.com/wiki/Category:Mystical_Artefacts
https://cthulhueternal.com/open-mythos-artifacts/
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2586181842
https://www.quora.com/What-are-some-powerful-artifacts-from-the-Lovecraft-universe

*Most faiths have an emptiness inhabited by some primordial form of chaos.

I think char modifiers would be a great addition instead of just stats increase. It would allow for further customisation to related artifact and can be lost on certain conditions.

Also making a decision to get Immortality trait with certain artifacts but getting witch trait, losing your personality traits with their counterparts would be fun

If you dont know how to include custom event chains into game, i can look into that for you and perhaps help you with writing them. just let me know

https://en.wikipedia.org/wiki/List_of_Cthulhu_Mythos_books I will delve further into books mentioned in here to see if i can find additional info of them, perhaps they could be interpreted as journals idk

This is awesome, thank you and I'll get working on that asap.