There are different rarities and forms of weapons and armor, their name are labeled in different colors:
Yellow: A common version of a weapon. These can be crafted by Artisans.
Blue: An uncommon version of a weapon that has boosted stats (Grand, Golden, Demon, Dark, Elven and Legend prefixes) or a lower level requirement (Saint prefix).
Purple: These are very rare and special weapons. Unique weapons, easily detected by their purple names, they are weapons with no level requirement and only require fairly large amounts of their weapon type's significant stat, usually ranging from 150~200. Regardless of their name, unique weapons aren't unique, but very rare. Each unique weapon gives a fixed bonus of their own, usually a very substantial advantage. Unique weapons are never prefixed.