Probably i'm missing something, but i don't think it's possible to balance Arms in it's current state.
If they tweak the numbers so it stays competitive in heroic gear, in lfr/flex/normal gear would be ahead of every other melee given how bad it scales with everything besides weapon damage.
I don't dislike the idea of being ahead for 2-3 weeks, but i doubt that would be the case, i guess that they'll tweak the numbers for normal gear and, once everyone is in hc gear, arms will fall behind again.
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If the damage of deep wounds is increased even more, they should make MS increase the duration and TC apply the dot, MS'ing with 10 feather stacks was the worst feeling ever knowing that 1-2 ticks later i would apply a crappy DW no matter what.