Just items. I think there are no armor enchantments that add direct damage, and no magic damage charms. Weapon enchantments obviously aren't an option, so you can only increase it from jewellery.
But really, there's not much point in trying to go for high magic damage on an unarmed character. Unarmed by its nature does normal, Strength-based damage. You can get magic damage on jewellery, but that same jewellery can also get Melee-damage based damage, which will have a much stronger impact than the same amount of Magic damage.
