Obscuridad del Santo Andres

 is an item found in Red Dead Redemption.

Characteristics
"A blessed symbol from a far-off land. Enemies have less chance to hit you."

Locations
Outside of Las Hermanas (the nunnery). I believe it happens between noon and four and you must have hero status honor. It has a bit of a random aspect to it. A nun will appear just outside of the Las Hermanas building on the road and offer you a gift. Press B to accept it.