I think the hand is Midna. In her imp form, the hand has the same shape as her hair-hand. It even has her twilight zig-zag pattern on her arm. Also, zoom in on this GIF. Do you see that figure next to the mummified corpse? Doesn't it look suspiciously like Midna in her true form? You also might notice the sealing spell writing is in gerudo. It might be Nabooru, but maybe Midna is a Twili version of a gerudo?
Read the instructions and have your mind blown. I love LOZ and have been sOO anticipated for the new game! I've been trying to resist the news easter eggs on it but I've already seen too much. ;-;
