Skyrim Auriel's Bow

Auriel's Bow enchantment deals 20 points of sun damage. This damage is tripled if the target is an undead, such as a Vampire or Draugr.
Auriel's Bow appears to have faster draw speed than a regular bow. Fully nocking an arrow with Quick Shot perk takes less than a second.
The bow is acquired in the Inner Sanctum within Forgotten Vale. It is obtained at the end of Touching the Sky, after defeating Arch-Curate Vyrthur.
It can be upgraded with a Refined Moonstone ingot at a grindstone and also benefits from the Elven Smithing perk, which doubles the improvement.
This will also give you the achievement for using Auriel's Bow