Here are the blacksmiths inventory specialities for each hold:

Solitude:
        Guaranteed Moonstone ores/ingots available 10 levels earlier.
        Elven weapons and armors available 10 levels earlier.

Dawnstar:
        Guaranteed Quicksilver ores/ingots.

Windhelm:
        Guaranteed Malachite ores/ingots available 10 levels earlier.
        Glass weapons and armors available 10 levels earlier.

Orc Camps:
        Guaranteed Orichalcum ores/ingots available 10 levels earlier.
        Orcish weapons and armors available 10 levels earlier.

Riften:
        Guaranteed Ebony ores/ingots available 10 levels earlier.
        Ebony weapons and armors available 10 levels earlier.

Markarth:
        Guaranteed Dwarven ingots and Sliver ores/ingots available 10 levels earlier.
        Dwarven weapons and armors available 10 levels earlier.