Esra and the fall of Shethalas
Cold wrought iron
Cold wrought iron, the heaviest and strongest iron in the land. It is blacken mixed with bluish hews. Cold wrought iron is very difficult to shape, sharpen and use. This is due to its extreme weight and hardness. A suit of full plate armour weighs 120 lbs. The main weapons made from cold wrought iron are war hammers and mauls, other bladed weapons are too difficult to make. On heavy blows such weapons have been seen to crush armour and break shields.
In game mechanics
Cold wrought iron armour requires a strength of 18 to even attempt use of such armour. The advantage of such use is that on an enemy roll of 1 (critical failure) weapon dulls or weakens(-1 to hit). Cold wrought iron hammers require a strength of 18 is required to wield without disadvantage. On critical a coldwrought iron hammer will damage an enemies shield or armour -1 to AC