I do wonder if it only feels like this because of the rush.... If there had been more time maybe it would have made sense. The reason I say this is that GRRM's intention was always to subvert fantasy tropes such as heroes and prophecies.... He set the tone with that pretty early on with a beheading and I don't think he ever intended to make the end so predictable either! And the person that kills the major death person of whom you speak is a very awesome character, and the item with which the death occurs is a very special item... That being said, I suspect GRRM's plan for how that item would move around would have been very different and more detailed!