From the blog, “St. Peter’s List“.
Blessed medals are considered sacramentals.
Mine was blessed by Pope Benedict XVI, and I wear it every day. It provides considerable protection to the wearer. From my own anecdotal experience, I can say that while wearing it, I have never been struck by lightning or suffered the effects of poisoning. As for verifying the other protections it affords me, you will have to ask my guardian angel.