Amulets (charms) are an ancient concept and practice – dating back to pre-Roman and pre-Hebrew days, with the idea that some physical thing – a rock, a piece of wood, etc., could in some way deliver god’s blessing to the wearer.
This is followed today by people who wear crucifixes around their necks (or Jewish stars, etc.).
Of course, there is no evidence that wearing a piece of metal around your neck provides any magical powers at all.
If there is one thing that can be said for a charm, it is that the charm acts as a reminder of the person’s faith, which MIGHT have some indirect effect on their actions. Maybe,
But I’m not sure that holds water either. Look at the mug shots of a bunch of criminals or arrestees. A significant number of them are wearing crosses…. so the reminder to be good had no effect on their behavior.
As for me – no charms.