Having them under existing categories would work too, it just feels a lot better to have repairing integrated with crafting, and having crafting be more toward your character type.
Instead of just having your rogue repair and craft everything, he will repair and craft rogue gear.
Also, having a very high luck stat should be a viable alternative or accessory to crafting. I personally would have Loremaster and Enchantment both under Wizard, and not include repairing in enchantment, since wizards use magic so often that they rarely need to repair their staves.
