If you have problems with a warrior under 35% you are either a terrible player who doesn't know what to do or the warrior is popping cooldowns to stay alive. Take out second wind and a warrior will not have ANY healing whatsoever. It is not an automatic IWIN button either. Pretty much all classes can kill me while I am under 35%.
Oh, as for when a warrior is popping Avatar / Reck and whatnot, there are plenty of counters to it, I would be more worried about BM hunters over a warrior which can be kited / Disarmed / Stunned etc whereas a hunter can do their full DPS from 40 yards away