Furritung

Karnak is a Sword. It's propably the best currently available sword.

Crafting
It can be crafted by a Sword Smith at level 100 from 5 Aquamarine Stone, 1 Bone of the Pandora Ghost, 4 Bulbig Magic Bark, 3 Magic Holy Bamboo Root, 9 Pyrute, 9 Rutile, 15 Sacred Bamboo Wood, 5 Topaz.