This "Blood Sacrifice" talk reminds me of "Cabin In the Woods". Come to think of it, the physical layout of the Westworld park seem to be most similar to the environment that that movie takes place in.
I notice that Ford didn't deny that he killed Arnold. He just said that Bernard hadn't been created yet. I still think Arnold found a way to upload his mind on to the "beacon" computer that Elsie found, before Ford was able to kill his physical body. Then, years later, Theresa (who had no idea Arnold existed) reactivated the old beacon system to help the Delos corporate board to spy on the park. This allowed Arnold's mind to broadcast directly into all of the hosts in the park. Maybe Ford created the "reverie" patch to cover up the fact that Arnold is fighting him for control and he can't stop him.
Now I'm trying to figure out why Arnold had the young Robert robot kill the "killer" dog. Does the dog represent Bernard, since Bernard is a "killer" robot? Was that Arnold's real message to Ford in that scene?