The Celtic Long Sword was around three feet in length, with a straight, double-edged iron blade. Greek historian Diodorus Siculus descriped the Celtic swords as being "as long as the javelins of other peoples." The hilt had a very small guard, a single-handed grip, and (most noticeably) two backward-curving quillons near the pommel.
The Iron Age was introduced to Europe in 1190 BC (starting in the Aegean Sea) but would take centuries to expand to the rest of the continent: with Northern Europe being the last region to adopt the Iron Age in 500 BC. Many Celtic tribes excelled as Blacksmiths: with the Hallstatt Celts (Early Spanish, French and Germanic) having some of the earliest iron swords (estimated to be as old as 800 BC).
The Celtic long sword was primarily a slashing weapon, as the rounded tip was ill-suited for thrusting and stabbing, making it similer to the Khanda. The Celts were famous for their iron working abilities, and some historians even think that the Celts iron should in fact be classfied as steel. According to the show, Celts used the long sword from back of chariots as well. This was successfully tested as the long sword through the nose and to the brain from the back of a chariot.
The Celts prefered way of killing with the long sword was decapitation. After a battle the Celts would hang the heads of their decapitated enemies on their houses, their chariots and their horses. They would also stick the heads on a pole sticking out of the ground outside their house. The Celts kept the heads of their fallen enemes as a trophy and to possess a persons head is to posses a magic power.
When a Celt died he was buried with his sword. His sword was intentionally broken before burial so that only spirits like the deceased Celt could wield it.
As the Medieval Age raged on, the former Celtic tribes became more unified kingdoms; with the Scottish Kingdom lasting from Circa 800 AD to 1707 AD (although it technically still exists, it has been merged into the United Kingdom of Great Britain). The Scottish continued their infamous use of swords, frequently using the Medieval Broadsword and Claymore.
Spanish Celtic Long Swords would evolve into the Roman Gladius. Germanic Celts would influence Vikings; leading to their own variation of the Long Sword. The Celtic Long Sword may have eventually evolved into the Scottish Claymore.