I'll write something more lore-rich when I have a chance, but in short;

Brass: added the ability to make weapons and armor.

Slag: inferior to iron but made by goblins using iron and any common stone, stretching out their metal supply while reducing the utility of 'goblinite'.

Silversteel: A steel alloyed with nickel with superior qualities in all regards, limited to the elves. While the secret of its production is lost to the dwarven player, it can still be melted and reforged.

Bright Bronze: A bronze alloyed with nickel, again with superior qualities. The Zhan-Khaz dwarves use this metal extensively instead of steel, as do elven nations.

Eisenstahl: billets of eisenstahl are prepared by the Eislers out of wrought iron and hard steel, producing a somewhat heavier weapon able to bear a harder cutting edge without the blade shattering thanks to the softer iron supporting it.

Doesn't that mean non-dwarves have better weapons and armor than dwarves, you say? Well.

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