Lucky you, I've never seen it drop and I play since beta and got 12 chars on old server and 8 on new one. The only thing I see drop a lot is agent one, the inquisitor one and sometimes a bounty hunter one and once a marauder one.
The same goes for republic The Esseles btw, smuggler/consular gear a lot, trooper gear bit less and seen maybe 3 times a sentinel robe but never guardian one.