Yoshi P talks about Warriors- from Producer Letter Live @ TGS

[Lhun]

Defiance lowers DMG -25% and raises HP +25%. So yes. You do less DMG with Defiance on - Defiance modifies enmity gain.

I've seen a lot of "DEX effects Crit" or "DEX effects ACC" going on in this thread and it's making my head hurt. If you're testing DEX gains by using DEX accessories please take note of the secondary effects on your gear; Spinel gives secondary Crit + stats, and Electrum gives STR/DEX and ACC. DEX isn't giving you ACC or Crit gains.

Putting on my BRD gear while on WAR -> 70 DEX changed my Crit & ACC stat exactly: 0

Parry 359 - naked.
Parry 359 - decked out in all my DEX gear from BRD.

Parry is a completely separate stat from Dex that does not modify that number in any way. The rate at which you parry is directly modified by dex, and then again directly modified by the stat "parry". Dex does not modify "parry". The two together modify your rate of parry % chance in response to every enemy attack focused on you, except magical. It also works with aoe that isn't focused on you. The chance to parry is calculated every time there's incoming "non-direct, non-magical" damage.