Flash doesn't get resisted. They may resist the Blind debuff but the enmity is fully applied. Also you forgot about Circle of Scorn.
If I'm doing a speed run or a huge pull or whatever, I don't even bother doing combos. I just hit Flash until they're dead or my MP pool is drained.
According to the in-game description, Circle of Scorn doesn't generate enmity. I've never found it to reduce hate at all, going by the "hate bars" that number party members by their hate.
Here's the in-game description:
Delivers an attack with a potency of 100 to all nearby enemies.
Additional Effect: Damage over time for 15s, Potency: 30.
I will spam Flash as I feel that's about all I can do against a group of mobs, but I don't find it's as effective as using it a bit more sparingly alongside the RoH combo. If my DPS aren't on point I can hold hate just fine. I have long suspected that PLDs who do hold hate are only doing so because the DPS aren't up to par. When I play BLM, I almost always pull hate from a PLD.
it's already known that warriors have better snap aggro. When you're aoe tanking w/ pld are you spamming flash till your mana is pretty much empty? You don't want to use your combo very much when aoe tanking (just the mana combo after a while). Flash always generates the same amt of aggro (the blind is all that is resisted). Also Circle of Scorn is pretty useful too. Another thing is what weapon you're using, if you have a low level weapon you aren't going to hold threat against someone with a higher level weapon.
I actually find it works better to use Flash after 2-3 attacks instead of spamming. I've tried both ways though and it doesn't matter. Against good AoE DPS, it's extremely difficult to hold hate.
As I said above, Circle of Scorn doesn't generate enmity according to the in-game description, and I've never noticed it to have an impact, although I still use it. I see a lot of PLDs pull a group and immediately use CoS, then I promptly pull the hate from them. When they pull, then use Flash, it takes me a rotation or two to pull the hate.
When it comes to my weapon. I have Zenith for both my PLD and WAR at the moment. They're basically the same ilevel but tanking on WAR is a cake walk, while AoE tanking on PLD is considerably more difficult. It's not even a FFXI tanking challenge where you just had to be good at your job. I was a great TaruPLD in FFXI, but I don't feel PLD has the proper tools to hold AoE hate in ARR.
Don't use the Halone combo on a single target. Spread the hate around by using Fast Blade and Savage Blade on one target, then RoH on another. Make liberal use of flash in between combos. Start pulls with Fight of Flight for increased enmity.
I've never had issues tanking mob groups as a PLD main.
I also switch mob mid-combo. It's not enough because Fast Blade doesn't generate enmity and other jobs are hitting all three mobs simultaneously. I also use FoF and it doesn't have the desired impact.
Again, I feel people who have no issues holding AoE hate with PLD aren't partying with good DPS (or at least good BLMs). I have yet to find a PLD that can consistently hold hate against my BLM, and I have considerable trouble on my PLD (and no trouble at all on my WAR).
That is key though. And most DPS in dungeons gotta go fast, fast, fast, so you can't really use Overpower all that much, since no one will wait for your TP to regen between pulls. In the end as a WAR you still have to split your combo between mobs. Steel Cyclone is awesome though. Feel free to abuse that.
I've never had trouble with TP on my WAR no matter how fast we're moving through a dungeon. I monitor the hate levels of the other party members and that determines how often I use Overpower. I'll toss in Flash if need be, and mix in Steel Cyclone, but TP has never really been an issue on my WAR so long as I'm paying attention.