Captain America's weapon is the iconic SHIELD, which is a six-letter word. The SHIELD is a round, concave disc made of vibranium, a rare and indestructible metal found in Wakanda. It was designed by Howard Stark and given to Captain America by the US government during World War II. The SHIELD is known for its ability to absorb and deflect energy, making it an effective defensive tool. It has become a symbol of justice and heroism, and is one of the most recognizable weapons in the Marvel universe.