Nuada

Nuada (ヌアダ) is a Magic God of Celtic Mythology and a member of the true Gremlin, first mentioned in Shinyaku Toaru Majutsu no Index Volume 13.

Etymology
was the first king of the Tuatha Dé Danann in Celtic Mythology. He lost an arm in battle and was removed from kingship as a result, but was returned to the throne after having his lost arm replaced by one made of silver. His silver arm was the source of his epithet Airgetlám (meaning silver hand/arm).

Appearance
Nuada's appearance is largely unknown, other than the fact that he had a prosthetic left arm made of silver.

Magic God Invasion Arc
At some point around the time of the incident instigated by the High Priest, Nuada encountered Kamisato Kakeru and was 'exiled' by his World Rejecter. His silver arm is later returned before Nephthys