Dawnguard Rune Axe

 is a weapon found in.

Enchantment
This gives an added benefit to the Sun Damage capabilities the weapon already possesses, as every undead being that is killed by the Rune Axe will add to a kill count, which will, in turn, add to the power of the Axe's Sun Damage enchantment. The maximum power of the enchantment is achievable after ten successive kills. The axe's kill count will not reset if it is tempered at a Grindstone.

Acquisition
The axe is acquired during the Lost Relic.