The Romans had many weapons but the standard weapon for a soldier was his "gladius" or sword and his "pugio" or knife. He also had a couple or three javelins. The army as a whole had various types of siege engines and various types of catapults.
A method of hardening steel swords in the Middle Ages was the damascene process of thrusting a superheated blade in the body of a slave and then into cold water. Crusaders discovered, to their dismay, that swords made of Damascus steel were more resilient and harder than those of European manufacture. Europeans did not discover the secret until 500 years after the Crusades, however, when it was discovered that thrusting a red-hot sword into a mass of animal skins soaking in water had a similar effect to the Damascus method. The nitrogen given off by the skins in the water produces a chemical reaction in the steel.
The hastati contained the young fighters and carried body armour and a rectangular shield, the scutum, which should remain the distinctive equipment of the legionary throughout Roman history. As weapons they carried a sword each and javalins. Though attached to the hastati were far more lightly armed skirmishers (leves), carrying a spear and several javelins. Romphaia was a long double-edged sword. Spathi was the normal sword.
The Roman cavalry used a much longer sword, the so called spatha. Towards end of the second century that spatha gradually replaced the short sword also for the infantry. Its Length was 75 cms and longer. The shape of the blade is not easy to distinguish from the Germanic swords of the period. However there are two exceptions: The first century spatha looking like a longer galdius Pompeianus and the later thrid century spatha type Lauriacum-Hromowka:
The famed Fluvius Camillus made some significant changes to the armament of the legion according to traditional Roman view. As the bronze helmets proved to be inadequate protection against the long swords of the barbarians, the Romans credited him with the issue of helmets made of iron with a polished surface to cause the swords to be deflected.
By second century BC, the soldier now used the gladius, also known as 'the Spanish sword' to the Romans, apparently due to its origin. The iron helmets had now been replaced by bronze ones again, though of thicker metal.
Each maniple was commanded by two centurions, the first centurion commanding the right, the second the left of the maniple.
The historian Procopius describes the eastern horse archer as wearing a helmet, chest and backplate and greaves as armour, being armed with a bow, a sword and, in most cases, also with a lance. Also they had a small shield slung on their left shoulder.