Gladius

Gladius was the sword used as the standard and the primary equipment by the Roman Legionaries, since General Marcius, 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.

Because the blade was used by Roman demigods, then it was presumably made of Imperial Gold.

Design
The gladius has a comparatively shorter blade than ancient Greek swords. Possessing no crossguard 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 and moving about than the cutting and slashing of heavier and sturdier blades.

The Lost Hero
Near the end of the book, Juno presents Jason with a Gladius to replace his lost weapon Ivlivs which had been destroyed in the battle against Enceladus. This gladius has a leather sheath. It is currently unknown whether Jason's gladius is Imperial Gold or Celestial Bronze.

The Son of Neptune
Gladius's are standard issue to everyone in the Legion with the exception Hazel who uses a spatha and Frank who uses a bow and arrow.