In the enchantment, the bow is said to do 10 sun damage (It says 20 but is, in truth, 10: Skyrim:Auriel's Bow - UESPWiki) and does triple damage to the undead. Now, let's say I have Auriel's Bow at 80 damage. Would the bow with the enchantment be doing 80 damage + 30 sun damage against a draugr...