As a player working on crafting skills, I see a lot of potential for the use of materials other than steel in producing items...
1) One could use 1 steel and 1 brass ingot to make a handle for a sword. Such a sword would show a yellow crosshilt when wielded.
2) Maybe certain metals and materials take to particular magics more easily...so if you are a "Red Wizard", maybe your magic sword would hold more powerfull magics if it were made of copper, rather than steel...
3) For any crafted items....swords, helmets, axes, shields....I see potential for adding "accents" to the crafting process. Maybe one could choose brass, gold, silver, or even ruby and emerald "accents". This would be brass banding on a shield or the facegaurd of a helm..gold plated "blood groove" on a sword, or a gem studded pommel or helmet.
It seems that this would be fun, add to the economy, increase the value of crafted objects, lend itself to originality, and make the game more diverse if the proper graphics could be made to reflect the "Accents".
Say you make a round shield...it has a metallic ribbing around the edge and criss cross the front of the shield. Every round shield looks the same. If you use brass or gold accents, this band would be golden in color, much like choosing hair color on an avatar. If you use rubies and diamonds, it would show red and white studs along the bands. If every round shiled was identical in appearance, but for these accents, it would still show great variety and ascetic perference.