A short sword called The Gladius was the main weapon of the Roman Military. When people used the name: Gladius Hispaniensis or "Spanish Sword" it is thought that this weapon was based on swords Celtic warriors were using against the Romans in Spain.
The Pompeii sword was in good use by the 1st century AD and continued well into the 2nd century. The weapon has straight parallel edges and a short stabbing point. Blade widths average between 42 to 55mm with the length of the sword being 420 to 500mm. The Pompeii sword is equally suited for stabbing at close range.
About 100 AD an even shorter sword known as a Pugio was used.
Mainz swords have a blade width of 48 to 75mm and a length of 400 to 550mm. By the time of Augustus these swords were in “widespread” use. Possessing a long tapered point and slightly curved edges they were ideal for stabbing thrusts.
A legionnaire also carried two heavy Pilum javelins which could punch through 13 - 25 mm of shield and hide, making the shield near useless. Upon impact in shield or bone the Pilum buckled near its neck so it could not be used by the enemy. The long metal shaft prevented the javelin from being hacked off easily.
Accompanying the Roman legionnaires were groups of auxiliary troops including slingers and archers mainly recruited from captured armies.
The calvary accompanying a legion only numbered about 300 but this increased in later years as the armies facing Rome were started to build larger numbers of mounted infantry and calvary. The calvary scouted ahead of the Roman infantry and filled a vital need by carrying messages quickly between units. Gothic horsemen, in defeating Roman legions at the battle at Adrianople in 378 AD, marked the rising dominance of calvary over massed heavy infantry formations.