Narval is likely coming from Narwhal, an Arctic species of cetacean, which explains the water damage bonus. It has been involved in several legends; In Inuit legend, the narwhal was created when a woman holding onto a harpoon had been pulled into the ocean and twisted around the harpoon; hence the polearm weapon. Some medieval Europeans believed narwhal tusks to be the horns from the legendary unicorn.These tusks were considered to have magical powers; this is where the Healing Magic bonus comes from.