It is a shield. The Latin word is scutum and comes from prior to the empire. Prior to and after the Empire the shields tended to be oval or round. During most of the empirical period they were rectangular.
Excellent images can be seen of both styles by searching for "scutum (shield)" on wikipedia.
The pincipal weapon of the Roman cavalry was a sword called spatha.
a pike, which is a spear like weapon
yes
The roman army did not use nuclear weapons.
The "Short Sword" was the standard Roman Infantrymen's weapon.
The Roman god Jupiter's weapon is the thunderbolt, also known as the lightning bolt. It is a symbol of his power and authority as the king of the gods.
a mirror
it is a weapon used by poseidon
They used swords and spears
The 'boss' or 'umbo' in the center of the Roman scutum was used as an auxiliary punching weapon.
The Roman Army about 200 BC.
Mars, the Roman god of war, is often depicted wielding a spear or a sword as his primary weapon. In addition to these, he is sometimes associated with a shield and armor, symbolizing his role as a protector of the Roman state and its military. His weaponry embodies the ferocity and strength of warfare, reflecting the importance of battle in Roman culture.