Looking at the frame data shown here and here, I can see that it takes a berserker like me 12 frames + reaction time to switch guards. So I'm wondering what tactic I'm supposed to use against a class like the PK who has, in some cases, attacks that I literally cannot change guards quick enough to block.
I'm used to fighting wardens, so I'm used to the idea of preemptively blocking the AoE's and waiting for the inevitable overhead lights, but those are two directions, whereas the PK can throw attacks at me from all directions that I pretty much have to preemptively block. I can be quick but I'm no fortune teller!
Recently I've given up trying to block PK's almost entirely and gone for an almost completely offensive style against them, but I typically find my follow-up heavy is almost always parried - something I can understand, as when I fight other 'zerkers I will either block the lights or, failing that, anticipate the follow-up heavy and parry that, punishing the 'zerker and often reversing the flow of the fight. I can and do feint the follow-up heavy to try land it in a different direction, but by that point I've often lost any momentum I gained and the PK is starting to throw her lights at me.
Do you guys have any suggestions for a berserker tactic vs PKs? So often I feel like I'm banging my head against a wall.
I'd recommend dodging more. You don't need to always block attacks, dodging against a peacekeeper is easy as you can dodge in any of the 3 direction and be good 90% of the time because her swings don't have much distance to them.
Other than that, I find that berserkers are challenging when they are aggressive and I try to counter their aggression with my own. Try to be aggressive until the PK begins to dodge and go for those dodge attacks, counter this by guard breaking. So, you'll get off 2-4 hits and then go for a guard break as the peacekeeper is going to dodge as soon as she can.