There is nothing wrong with WW. I use it quite a bit. It is actually a pretty decent survival skill since they buffed the Katari. You do need to realize when to use it and when not to use it. Venatori are pain for WW, as is any sword or shield guys. Demons you can WW to death, and keep full guard through most of the match.
I typically use WW, mighty blow, Combat Roll, and Charging Bull.
The truth is, you really only need 3 skills to dominate with the Katari. Combat Roll, Charging Bull, and Mighty Blow.
I really don't like warhorn at all. The animation takes to long, and then you have to chase enemys down
The Katari survives by staying on the moved when engaged with the enemy (Charging Bull, Combat Roll, attacking), and by knowing when to lay back and not engage. There are some good videos out there that show how evasive the Katari can be with just those abilities.
For defense passives I'd take bear mauls the wolves, and the one that gives you stamina back.
When I play I can afford to be alot more aggressive since I do have a HoK ring, but in groups I rarely need it, because my guard stays half to full most of the match.
For soloing, I do rely on my HoK ring though.