Drops of ether is good if you play with people who actually use it. If you play with pugs heavy armor is better in my opinion. But yes our 3 must have engravings are expert/BA/ Awakening. The 4th and 5th are personal choice and they will not give you some wow power spikes.
get rid of heavy armor and shove a judgment in there for extra guage goodness.
After that you are free to go whatever you want, personally I shove a dps engraving like grudge or barricade or raid captain. drops of ether for support