With the change in heavy ammo economy in the crucible, you are going to have to adjust some of the story quests that require heavy weapon kills in crucible, such as the Shaxx quest: Honing the Edge. Getting sword kills in the crucible is hard to get as it is, now with only 1 heavy ammo drop in pvp, it's going to take forever to get 25 kills.
Mayhem is unchanged (which can be easier given the frequency of heavy drops).
Find a friend and cheese it in free for all (classic allows fireteams)
Still not that difficult.