Guide to PvP in my opinion.
In PvP, you want to avoid skills that take too long to charge, or charging skill in general while they have higher damage than quick activation skills, they don't worth much if you got damaged and they get cancel. You should always have at least 1 close combat karma and 1 range karma so you can respond the different situation.
Example: They are running away, close range karma like Great Sword and Blazing Fist is not gonna catch up to them. So you switch to long range to at least deal some damages.
Great Sword: This karma have longer range than Blazing Fist but action speed is slower and easy to cancel or avoid and a lot of skills of this karma force you to stay in place making you an easy target in exchange for more damage if you do land them.
Blazing Fist: Range is shorter than Great Sword in exchange for quick attack and easy combo tho the damage isn't as good as Great Sword in many cases, it has better potential in a 1 V 1. Because if you do the combos correctly, you can take off at least half their health bar or more if they don't cancel it out by dodging. If you grab them mid air and then landed, you can then throw them up in the air again to repeat your hits and then repeat.
Archer: This class is very versatile and can be really annoying, however it have a flaws that most of it skill can be dodges if not outright cancel before they even fully activate it, making most of its useless in PvP except for Storming Arrow, this one is quick and easy to activate making it the best skill for Archer but it doesn't have that good of a range. Hit and run tactics seem to be best one for this karma.
Mage: High damage however most of it skills is area so you won't get the best damage out of it, it's easier to hit it skills than Archer. However it is easier to cancel this Karma skills out than Archer since most it skill are charge skill. But this skill probably have the best Ultimate with stupidly large area of attack.