"It cuts off arms from the shoulder, heads from necks with a single hit, leaves the entrails out and produces all kinds of horrible wounds".
So told Pliny the Elder, in his Naturalis Historia, about the charms of the most feared weapon in the pre-Roman era. In the 2nd century BC, after the Second Punic War, the Roman Empire had expelled Carthage from the Iberian Peninsula. Now this territory was on a plate, and with it, its iron and copper mines, the richest of the Known World. However, a general uprising of Iberian and Celtiberian tribes against the invaders prolonged their conquest for almost two hundred years, and became hell for the Roman Legions.
The fierce resistence the natives opposed was influenced by their better knowledge of the terrain and their guerrilla war, but the use of the falcata, a sword clearly superior to Roman weapons, hit hard in the legions' moral. Augustus even orderd to renforce with iron the shields of the armies that left for Hispania, to try to mitigate its cutting effect.
The falcata's probable origin is the Greek kopis, a type of saber that Greek merchants brought in their colonial missions. From 5th century BC, Iberians gradually transformed it, decreased its curvature, added a double edge at the end (so that it could also operate as a thrust weapon, and especially improved its method of fabrication by using very pure iron and a three-plates structure. This lead to a very flexible weapon which was virtually impossible to break by other weapons of the time.
Its cutting power was most effective when used from high, such as in cavalries or at the defense of city walls. That is why, because of its characteristic shape, the hit came in a direction tangent to the target, and not perpendicular such as in the Roman gladius, so the cut was deeper. This technique has been later used, drom the scimitars to the modern sabers that Napolean dragoons used.