You know, if you have this question, you're on the right track. Remember, the secondary stat is super duper important when it comes to weapons. Secondary stat will affect how much boost your specific stats will get and enhance the character's damage potential. Prototype Archaic features ATK% and Whiteblind features DEF% secondary stat. If you have one billet, go for Prototype archaic. If you're in the early game, Whiteblind is tempting. But besides her, it's not much use on other claymore characters. Prototype Archaic will give you flexibility, and you'll have a versatile gameplay option.