I'm aware that your theories have evidence to support them being different people, but in my mind the story comes first. The story clearly calls for Shin Malphur to witness first hand the transformation of light to dark, hero to villian, to see the horrifying consequences of being that beacon of hope to everyone but yourself, it means you are your own worst enemy. Jaren Ward indeed lost his war to Dredgen Yor and he was murdered that night. It was when he saw that his legacy, his rose was the thorn.