Sentinel +4

Sentinel is an enchanted medium shield +4 which offers an armor class bonus of -5. It weighs 3 lbs. This item appears in Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition. It's for sale at the weapons and armor shop in Ust Natha stores

In-game description
"A century ago, astronomers noted an unexpected comet coming to earth offshore of the Sword Coast. An odd occurrence, it was made stranger by the lightweight fragments of metal found days later by blacksmith Huffum Fuiruim, who cared little about celestial events. He fashioned the bulk of it into this shield, though the forging took months and the aid of several enchanters. "From the heavens? Nay, from my hammer!""