God, Danzo must have caught wind of the Sharingan's plot changing powers. There were many things I was expecting, but an arm with a bunch of Sharingan implants was not one of them. The face on the back that we saw, combined with the fact that the arm is sealed, makes me think that more than just the eyes were implanted: he probably has access to whatever sort of chakra the eye's owners had.

Also, they could all be Mangekyous: Danzo doesn't seem to have a lot of friends, but I have no doubt he would be willing to kill them all for some additional power. What is it with people casually ripping off arms lately. Maybe Madara intends to steal the Sharingarm!