In the prologue of LoC at Shayol Ghul, the Dark One says that Asmodean was "twisted by his weakness", yet he says that despite the fact that Rahvin was loyal, even he cannot undo balefire. He kinda considers Asmodean irrelevant, but I am not so sure that balefire was used to kill Asmodean. Prior to reading that (I'm actually doing a re-read of the series and am right there), I had strongly felt that balefire was used, especially the way the ending is phrased "the words still hung in the air", like that was his last remnant. And that is possible with balefire, because it's not meant literally, but rather figuratively. Anyway, just wanted to mention that in response to the original theory. The rest is possible.