Shield is a piece of armor used for defense in battle. Moroni prepared the people of Nephi with “breastplates and with arm-shields” and “shields to defend their heads” (Alma 43:19). The Lamanites were not armed with “breastplates, nor shields” and were afraid of the Nephite armies because of their armor (Alma 43:21).
A speaker said, “it is your breastplates and your shields that have preserved you” (Alma 44:9). Moroni “fastened on his head-plate, and his breastplate, and his shields” before taking a pole with his rent coat at its end (Alma 46:13). They contended “with their swords and with their shields” all day (Ether 15:24).