Thanks for the responses. Very helpful. I do plan on pvping quite a bit.

I'm new to the game and nearing lvl 50. I plan of having different sabers for pvp and pve. I'm close to getting the black green crystal from the world event. My question is, should I get the 41 expertise crystal? Or is expertise better suited for finding it on other gear? And if not expertise, I'm assuming power would be best for a sentinel.