It seems that Link is somehow controling that turquoise hand. Gamexplain has uploaded an analysis of the trailer where you can clearly see how Link uses some kind of power with his hand that turns it to a very similar colour. What intrigues me is the fact that the "hand" over the dead figure, the one Link is supposedly controlling, has claws in the shadow over the wall. Can this mean that Link will have, or will transform into, some sort of evil "alter-ego"?
Hmmm....what if Link becomes the villain and Zelda has to rescue him from this evil force?