A. Shield Oath/Defiance will flat out hold with no issue against Halone spamming PLD in Sword Oath, regardless of accessories.
B. Turning off Defiance is your DPS stance.
I'm quickly learning that this is your go to catch phrase.
Stance Dancing PLD is the only way to do it, man.
A: I can steal enmity off Vit specced PLD's easily if I'm using full STR accessories, even with Defiance off. Yes I can probably hold against a STR specced PLD in Sword Oath, but because they're going to be constantly spamming Halone, I suspect I'd need to spam BB's Combo's to stay ahead. Which means no Storms Path, no Storms Eye, no Maim, etc etc.
Should be able to weave these things in with good use of Unchained and Berserk, but with just baseline skills, I'd be a bit dubious.
B: Not really, yeah you do higher DPS out of Defiance, but it's still just our baseline attacks with no modifiers. Sword Oath has an actual damage modifier attached to it, albeit in in the form of more powerful auto-attacks. Once PLD's get an actual DPS rotation to use, their Sword Oath DPS will outright trump Warrior out of defiance DPS.
Granted, Warrior has more offensive cooldowns, buuut, Sword Oath has no time limit to it's use.
Mind you, Warrior's could get more potent DPS abilities in the expansion, and render all of this entirely moot.