Signed.-blam!-ing signed. The mythoclast was my favourite weapon I would use it the entire year one before it (what they described as a trophy weapon that should be better than the rest) became useless
Get over it. Destiny is an MMO (or atleast somewhat is). Do you use gear from the first raid in WoW to beat the most recent raid? No, you dont.
Go get one from Y1 and use it in the Crucible.
Don't worry, it'll be back eventually. It's been my opinion for a while that bungie would revive the old raids for the next April update, it makes too much sense for them. It would generate a lot of goodwill, and give people a reason to play up until destiny 2.