My thoughts for a Warrior change, no new abilities
For Defiance, if it was +25% HP and +25% healing received, that would be a huge buff to the healers as well, making the HP scale easier. Given that there would be a buff to healing, already, I would like to see the stacks of Wrath give %parry instead of healing received.
Also, a significant change that would make one ability that, while cool in concept, isn't effective at all in pvp, is Holmgang. If you removed the self-root and instead put a buff of +40% parry on it, making it a 6s root on target and a 40% parry buff for at least 12 seconds, that would put it very close in line with Bulwark that the paladins have.
And speaking of Paladins, a very beneficial change with that would to be to change the cross-class ability from Convalescence to Rampart, this would give us a more beneficial cooldown ability to use, while doing nothing as far as creating a new ability. Paladin gets our -20% damage taken effect, adding to their repertoire of useful abilities.
Warrior Change, continued
Another small change would be to make Foresight and Bloodbath also give stacks of Wrath, giving us even more access to the self-heals we have and taking stress off of the healers.
I kind of want to see Warrior become more friendly to Parrying to compensate for the lack that a shield would give us. With these changes I have mentioned that, in all reality, are not game-breakingly huge, I would say it would buff us to being at a competitive level with Paladin.