How significant? For starters, armor penetration has been utterly removed from Battle Stance. Instead, it now simply grants a warrior an extra 5 percent damage dealt and 5 percent less damage taken. Defensive Stance grants 45 percent additional threat and -10 percent damage taken, with no damage dealt penalty, and Berserker Stance grants 10 percent damage dealt and no damage taken. In many ways, this is merely a way to make the stances all seem positive (much as how rested XP was changed from a penalty to XP when you didn't rest to a bonus when you did), but it's still nice to no longer take more damage than anyone else just because you decided to DPS as a warrior. Tanking without a damage penalty no other tank pays will just feel better.
First off, Plate Specialization is now trainable at level 60, giving arms and fury warriors more strength and prot warriors more stamina when wearing plate. To give you an idea of how mastery currently works on gear, we'll first reprint the bonuses and then show some examples of it scaling.
- Fury Increases the benefit of abilities that cause you to be enraged or consume an enrage effect by 80%. Enrage abilities improved further by mastery rating.
- Protection Increases your chance to block by 10% and your chance to critically block by 10%. Chances increased further by mastery rating.
- Arms Grants a 16% chance for your melee attack to instantly trigger an additional melee attack for 50% normal damage. Chance increased further by mastery rating.
Now, to get an idea of what that mastery is doing, here's the same warrior switching out his mastery gear for older, non-mastery gear to reduce his mastery rating to baseline. What happens to Death Wish?
You can clearly see that Death Wish without any mastery from gear loses almost 8 percent of its damage increase. Mastery for a fury warrior interacts this way with any enrage effect or effect that consumes an enrage, meaning that Enraged Regeneration will heal for more, and Enrage and Death Wish will provide more damage as your mastery rating increases. And since arms and prot each have their own mastery bonuses, you can easily imagine a situation where a mastery trinket or ring could be of use to any spec.
In addition to all this, we have some other changes. Leveling warriors who haven't earned a talent point yet will gain a new ability: rather than starting with Heroic Strike, they gain Strike. Strike is clearly intended to replace HS and to be itself replaced once you hit level 10 and gain Mortal Strike, Bloodthirst or Shield Slam as your spec-based ability.
The protection passive ability Vitality is now Sentinel, granting 15 percent additional stamina and increasing rage generated by 50 percent when attacking someone not targeting you, most likely designed around off tanking. Rage generation has been increased by about 50 percent, but critical hits no longer generate extra rage, which ultimately seems so far to be working out (based on very limited testing by me in Deepholm) to almost the same rage generation and much less spiky overall.
Overall, you're definitely going to want mastery gear as soon as you can get it. It makes a huge difference.
World of Warcraft: Cataclysm will destroy Azeroth as we know it. Nothing will be the same. In WoW.com's Guide to Cataclysm, you can find out everything you need to know about WoW's third expansion. From goblins and worgen to mastery and guild changes, it's all here for your cataclysmic enjoyment.