Fatebringer won't be obsolete by HoW. Just because it's a 300 atk handcanon doesn't mean that the next raid handcanon will out do it by a long shot. Just look at the word of crota. Overall damage is only higher by about 10 damage, or somewhere near that. For all we know the next raid hand canon might have less impact to compensate for the higher damage value it's given. With that being said, I wouldn't be so quick to dismiss the fatebringers longetivity.