Cold iron armor sickens certain creatures that touch it. A creature with weakness to cold iron (such as most demons and fey) that critically fails an unarmed attack against a creature in cold iron armor becomes sickened 1. A creature with weakness to cold iron is sickened 1 as long as it wears cold iron armor.
High-grade items use the purest form of the precious material, and can be used to Craft magic items of any level holding any runes.