The Gladius is a sword used as the standard and the primary equipment by the Roman Legionaries since General Marius, and is a common weapon of the Roman demigods. A fully equipped Roman Legionary was armed with a shield, several javelins, a sword, and often a dagger. Conventionally, the javelins would be thrown to disable shields of enemies before engaging the enemy, at which point the gladius would be drawn. The soldier generally led with his shield and thrust with his sword.
The Gladius was gradually replaced by the Spatha by the 2nd and 3rd Centuries AD.
The gladius has a comparatively shorter blade than ancient Greek swords. Possessing no cross guard and a large pommel, the sword was forged with a lighter and consequently faster blade. The gladius required a fighting style more based on thrusting than the cutting and slashing of heavier and sturdier blades. They were generally made of steel in Roman times.
Technique and advantages
The Gladius played a major part in Rome having the one of the best armies in the Ancient World.
The Gladius was generally used after the javelins had been thrown, hopefully disabling the opponent's shields. The Legionaries would generally lead with their shields and follow up with quick stabs to the abdominal area. The blade was best designed for stab wounds, but could also slash.
The Gladius's shorter length gave a distinct advantage to the Romans, as it was more suited to fighting in very dense formations than a longer blade would be.
In the book however, Romans are able to transform the blades into Pilums, the Roman Javelin. It is unknown if all Demigods can do this, considering only Jason and Reyna displayed this ability during the events of The Blood of Olympus.
Near the end of the book, Juno presents Jason Grace with a Gladius to replace his lost weapon Ivlivs which had been destroyed in the battle against the giant Enceladus. This gladius has a leather sheath.