Miraak's Sword

 is a unique weapon found in.

Acquisition
Miraak's Sword can be looted from Miraak, along with his staff.

Enchantment
Absorb 15 points of stamina. In additon, it will turn into a long tentacle when swung. Though it appears to have a long reach, it does not.

Trivia

 * Miraak's Sword has the highest base damage of any One-Handed Sword in Skyrim.
 * This weapon also has a very low weight, having only a weight of 3. Weapons capable of the damage that this sword can do often weigh in the double digits.
 * In order to improve this weapon, the player must have Daedric Smithing, an Ebony Ingot, and a Daedra Heart.