Since earliest times the sword had been the weapon of choice for the Roman legions. Sometime in the 2nd century, the longer cavalry sword, the spatha, replaced the short gladius as the primary weapon of the foot soldier. The gladius measured on average 40-50cm while the spatha were commonly 65-70cm long. It is thought that a change in fighting style was the main reason for the change in sword. The gladius seemed suited to fighting at close quarters from behind the traditional curved rectangular shield, while the longer spatha was better used when fighting with a large oval shield. The spatha gave the legionary the reach he needed to get around this oval shield. A legionary's sword was fundamental to his role as an infantryman. It was his primary killing weapon, used to stab and thrust, as before, but also capable of slashing and hacking at the head and shoulders of a fleeing soldier.
"...they learned to strike not with the edge, but with the point. For the Romans not only easily beat those fighting with the edge, but even made mock of them, as a cut, whatever its force, seldom kills, because the vitals are protected by both armour and bones. But a stab driven two inches in is fatal; for necessarily whatever goes in penetrates the vitals. Secondly, while a cut is being delivered the right arm and flank are exposed, whereas a stab is inflicted with the body remaining covered, and the enemy is wounded before he realises it." Vegetius Book 1:12
In man-to-man combat the sword was used to stab into the body of a foe, but when engaging a shielded target the long spatha could be used to reach over the shield to strike the head or neck, the shoulders, the sword arm, or the left leg (which usually led) and was easily visible below the shield.
Good view of Demetrius' spatha, his tunic is decorated with a pagan good luck symbol, known today as the swastika
Spatha were not crude mass-produced weapons, they were carefully wrought swords, often with pattern-welded blades. The hilts and pommels were crafted from wood, horn or bone - all organic materials. In earlier centuries the legionary sword hung on the soldier's right side, but in the 3rd century, soldiers wear their swords on the left. Swords sat in a scabbard of wood, sheathed in leather. To protect the tip of the scabbard from knocks a metal or bone 'chape' was fixed to the scabbard tip; to allow the scabbard to be slung from the shoulder or the waist, a bracket of iron, bronze or bone (a scabbard 'slide') was fitted close to the top. Through it a leather baldric was wound, and this allowed the legionary to wear the sword from his shoulder, as he preferred. The baldrics were always decorated with round phalera (patterened bronze discs).
This is Fortunatus' spatha with its scabbard and attached baldric. The grip and pommel are bone, the chape (the scabbard protector at the end) is bronze. The grip is a copy of one found at Buch, the circular chape was very popular throughout the 3rd century in Gaul, Germany and the Danube area. The decorative bronze disc (phalera) on the baldric is a copy of one found at Zugmantel. The originals are depicted below.
Above. The first, second and fourth swords from the left are all third century spatha, with scabbard slides and 3rd century box chapes. Two are made of bone, which are the commonest form of box chape found in Britain. The ring pommel spatha (second from left) harkens back to the 2nd century.