I see no one has answered you yet, so I will, and though my experience as a zerk is not great, I have lived in 50 pvp for quite a lot.
YES shield zerk works, don't worry about that, and if you feel like you cannot afford to make too many weapons, having shield and hammer is certainly good, because it gives you surivability and quite some dps when the shield procs. I am not sure that you have the time to switch to axe when the hammer procs and also, you will hope for the hammer to stunlock the other ... idk really how much more attack does the axe give, with masters and all.
I found one thread specifically for 50 pvp, it has some different builds:
So, good luck (in what server are you playing,btw?) and do your masters!