The secrets of ironworking are all but unknown in the Tiers. Iron weapons, tools, and armor are made almost exclusively by the Forge-Bound, mage-smiths under Kyros' rule. While iron ore is found throughout the Tiers, it is used for little more than weights and piled earthen walls; for the smiths of the Tiers have yet to master the techniques needed to shape this stubborn metal into contoured forms and keen edges.
Creation of iron weapons and armor is the sole purview of Kyros' Forge-Bound mage-smiths. Only they have the knowledge and power to smelt iron ore and retrieve the valuable metal. This secret of iron has enabled the Overlord to supply vast armies with iron weapons and armor. Where even the wealthiest of nations could only field bronze-clad armies of a few hundred soldiers, Kyros' forces number in the tens of thousands.
Unlike bronze weapons, iron arms do not require an alloy to create, making it possible to forge armaments from a single supply of iron ore. While iron is heavier than bronze and tends to shatter, the ease of replacing iron weapons makes them more desirable for Kyros' forces.
To maintain the advantage of numbers, the Overlord has decreed knowledge of how to smelt iron forbidden to all but the Forge-Bound. Possession of this knowledge, or even possession of iron weapons and armor outside of the military, is punishable by death.