Is there any chance that these could become ritual foci for someone with the improvised rituals feat?

> While I can see it looking interestingly thematic, it seems a tad overpowered to replace the cost and weight of a ritual focus with a spell slot.

I'd be fine with being required to destroy a ritual focus to unlock this feature. Maybe as part of a quick quest to unlock the ability. I don't think the weight is generally concerning, as you can pick up generic, small, and general worn ones from hallow's eve.