The "broken weapon parts" can be obtained in a few different ways

1. From children
2. From khajiit caravaners
3. In some Nordic ruins
4. Dawnstar near the invisible chest

and the max smithing skill you will need is 'steel smithing'


the repaired versions of the weapons are under iron smithing catagory, and the Steel versions are under steel smithing catagory and requires steel smithing perk


in the future (i dont know when) there will be repaired versions of the following:

Dwarven, Elven, Orcish, Glass, Ebony, Glass, Daedric and maybe Dragonbone