I use a shield + Dark Ward in Huttball, because I'm usually the ball runner there and every bit of damage mitigation helps.
In the other warzones I'm rocking a focus and therefore don't use Dark Ward.
Also, I don't know why people say that shielding doesn't do anything in PVP. I find a HUGE difference in survivability between my 0% shield chance with a focus and 35% chance with shield + dark ward. Especially in random zergs I shield a lot of attacks.
You can shield (almost) every attack from both Knights and Gunslingers, and some attacks from both Trooper classes.