Can you equip the luck charms just prior to opening a chest and have it make a difference? I stopped wearing all the luck things because I wanted some other charms more - like stamina.
I had my main character equipped with a bunch of luck and saw no difference in what I was getting. But maybe I didn't have the luck high enough - +10 shoes, +10 belt, etc.
Do you put points into luck? I never have. Perhaps I should.