The reason they originally increased the damage of the Mythoclast was to bring it back in line with how it performed in PvE before the nerf, and also to make it an effective weapon going into Crota's End. Two weeks after the launch of the expansion and most of us should have multiple 331 weapons by now, and many alternatives to the Mythoclast. I still use it for the agility when carrying the sword, but I could quite easily use a 331 Suros, or better yet; a 331 MIDA. In short, the Mythoclast is dropping back out of sight and will soon be forgotten, unless they bump the damage up to at least 331 via Xûr. That being said, it isn't much of a leap in damage; considering you'd have to spend 2 Shards and a bunch of time levelling it back up.