Well, it seems that no matter what, Dawnguard HAS to be uninstalled, then reinstalled to get Arcwind Point Word of Power. Thing is, it isn't going to matter which word, because any of them will do this at Arcwind. You lose EVERYTHING you did on Dawnguard, you can't save it to another medium, as when you put what you saved back into the game, Arcwind Point never happened. And, you cannot get Arcwind Point unless you have Dawnguard installed. When you do that ALL of the Dawnguard quests, or ANY quest you did with Selana is GONE. Bethesda has really disappointed me at least! They know this is a major issue, yet have done nothing.