 Celtic warriors are described by Polybius and Plutarch as frequently having to cease fighting in order to straighten their sword blades.This claim has been questioned by some archaeologists, who note that Noric steel, steel produced in Celtic Noricum, was famous in the Roman Empire period and was used to equip the Roman military.However, Radomir Pleiner, in "The Celtic Sword" (1993) argues that "the metallographic evidence shows that Polybius was right up to a point", as around one third of surviving swords from the period might well have behaved as he describes.