Honestly, spending Clearcasting already gets us a 20% damage amp to Barrage. I feel like Harmony is kind of redundant.
My biggest issue - and I will keep banging this drum - is that we are overly reliant on Arcing Cleave + Resonance for damage. Logs show consistently that Arcane does decently on 3-5 target fights (i.e. Vexie and Stix), but suffers badly on pure single target and falls behind on mass AoE.