Which defender's rifle is in a display case inside the shrine?

The defender's rifle in question is likely a reference to the Tomb of the Unknown Soldier at Arlington National Cemetery in the United States. The rifle, known as a "Tomb Guard Rifle," is a ceremonial weapon used by sentinels who guard the Tomb 24 hours a day, 365 days a year. It is a symbol of honor and respect for all unidentified and fallen soldiers. The rifle is displayed in a glass case as part of the Changing of the Guard ceremony, which is a highly revered tradition.