The Celtic Sword
From the way we are taught history, you might expect that the ancient Celts adopted most of their technology from the 'more civilized' Romans or the Greeks. In reality, it was the other way around. The Romans especially borrowed heavily from Celtic technology, especially military equipment. The Romans eventually copied their helmet, their mail armor (which the Celts invented), and their swords from Celts (the sword was a variety they ecountered in spain, somewhat different from the type featured here. The Romans called it 'Gladius Hispaniensis').

Two major centers of Celtic culture have been identified by archeologists. The first, at the site of a salt mine in the wooded mountains of Austria (Hallstadt), dated back to at least the 6th century B.C. It was identified as the manufacturing center of exquisite bronze and gold artifacts for Celtic tribes throughout Central Europe.
Replica Bronze Sword of the Hallstadt type from Antiqua Nova (Left)
Hallstadt era Replica Celtic Bronze Swords from DEEPKA (Right)
The second, at a lake in Switzerland (La Tene), represents a later and more highly technologically developed culture with exquisite metal-working skills, in what became known as the "Celtic Iron age".
Indeed, the Celts were possibly the premier metalurgists in the world during the peak of their culture, the 'steely iron' they were able to produce enabled them to become probably the first people to produce long swords out of iron (Celtic swords from this period were often as long as 33"-39"). The Celtic iron age lasted from roughly 300 BC until the last major bastions of autonomus Celtic culture were broken by the Romans by about 50 AD. (Celtic culture did continue to thrive for several hundred years in relative isolation in Ireland and some of the smaller british isles)
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Celtic warriors were, to paraphrase the Geto Boys 'crazy as @$%#' in combat, often fighting naked!
Celtic swords were single handed slashing and chopping weapons designed for use with a large shield, though they could also be used for stabbing.
La Tene period Celtic sword from Albion Armorers
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Models of Celtic Warriors from Pegaso Models
Some of the most important and famous Celtic artifacts discovered