I’d better look this one over again. I’m not sure an item can be the source of Grace because God is the only source of Grace. I think items can be a reminder, but not a source.
If an item can be a source of evil then it can be a source of Grace because the evil one always mocks God. Now of course the actual source of evil is Satan and the actual source of Grace is God but the evil or Grace passes through the “thing” in question.