It is a Dwemer staff that allows the wielder to summon a Dwarven Spider Guardian or Dwarven Sphere Guardian for 60 seconds. It can also, on occasion, summon random Dwemer scrap metals, such as solid Dwemer metal, large decorative Dwemer struts and Dwemer gyros.
It can only be crafted in the Aetherium Forge during the quest Lost to the Ages. Apart from the Aetherium Crest which is assembled during the quest, all other materials to craft the staff can be found in the Aetherium Forge room on tables to the left and right of the forge. [Source: wikia]
You can download the papercraft model here: The Elder Scrolls V: Skyrim - Aetherial Staff Free Papercraft Download