I'd like to point out that he was associated with it in Thorn 2 because they were in the City of Palamon, where Jaren lived, and that he later went after Yor for vengeance. After Dredgen Yor killed those three men, and supposedly razed Palamon to the ground (it mentioned Jaren and his "team" turning their backs on Palamon's ashes), Jaren grouped up with survivors from the city and went after Yor, looking to take the fight to him. Plus, Jaren wielded Last Word, not the Rose. And Last Word still existed after Thorn, so Last Word literally cannot be Thorn. Not to mention that the entire tragedy of Dredgen Yor was that his last comfort would be that people would remember him as he was before the transformation, and that they wouldn't remember him for the sufferings he'd cause. I think it's more tragic that we never get a glimpse of who he was before. All we ever hear about it Yor. And the reason Jaren's Ghost didn't revive him is because Yor presumably drained all of Jaren's Light, like he did to the "cliché bandit" and his three friends in that bar in Palamon. Ghosts can only revive people if they have traces of the Traveler's Light in them. There's just too many instances of Ward and Yor being at the same place at the same time. They're two different men, with two different weapons. Plus, Ward had literally no motivation to suddenly give into darkness; if anything, those "dead kids" would make him fight to save them even more before ending himself randomly in the woods one night. Go reread all of the Ghost Fragments for Last Word and Thorn, you get some blew information in Last Word 3 from The Dark Below that really nixes and chance of them being the same person.