I think there is a minimum hit rate for every skill in pvp. I think it is about 30%. This means that 1 in 3 (about) attacks will always hit even if the enemy has 1 million HV and you have 1 AC.
Extra AC and LK only bring the hit rate over 30%.
I agree that LK, AC and HV need to be changed. Hit rate should not depend on the difference of two people's LK. It should be more a percentage, or some other crazy thing where outlucking will help, but not as much.