sorry. i meant METAL. as in ALL types of metal. >.<
As Hiram said, the iron used is pretty much the same, but a big advancement was steel. And since steel is an alloy of iron, carbon and other goodies, there are a number of varieties that can be used for different purposes. But as far as advancements in materials used, the most advanced material is not a metal at all. Carbon fiber is becoming the material of choice in aircraft and advanced cars, buildings and defensive armaments, among others. The only limiting factor in its use is cost, which remains much higher than steel.
Modern day metal armor and weapons are made of steel, which is an alloy of iron, carbon, and other elements.
Much better in terms of uniformity. Weapons would be much less likely to break and armor much more likely to hold firm.
Iron, pretty much the same. They didn't know much about steel though.