Pommel strike is great - It's a guaranteed stagger/stun, which is amazing for CCing and killing off elites. An upgraded pommel strike has a duration (8secs) almost as long as its cooldown (10secs), which means that you can pretty much keep an enemy in a perpetual stun-lock. I would recommend it for almost any build.
Taunt is useful for threat management/tanking, although I personally don't see the need. It used to be relatively useful at drawing away enemies from your companions without causing friendly-fire, but post-patch you can usually get their attention with a few autoattacks. If you stay up the front dealing lots of damage and have a rogue with goad/armistice it's pretty much unnecessary. It's probably more of a thing for pure tanking, where the warrior's dps is too low to generate threat.
I like Bravery a lot, but it's rather situational and probably more useful for S&S than 2H. It takes up a crapton of stamina (30%), so it's not ideal for berserkers. Along with might and any other sustains/buffs you want to use, you probably won't have that much stamina to play around with. That said, fully upgraded, bravery potentially provides a pretty hefty bonus to critical chance and damage. Each enemy after the first gives +3% critical chance and +5% damage (and +%attack and +%threat) - I don't believe it's capped, so if you're surrounded by a lot of enemies, bravery can give you a massive damage bonus. If you do get it, I would recommend only turning it on when necessary (e.g. after you burn off a bunch of stamina anyway and are attacking a large cluster of enemies).
If i remember right, Tremor sucks. It's like a crappy small-radius mind-blast, without a guaranteed stun and with a tiny chance to stagger enemies. It doesn't really affect elites, and the enemies it does affect are those weak enough to not cause problems. Perhaps it may be decent on lower difficulties, but in my mind it's one of the more useless abilities.
If you mean battle synergy, you can't actually use it at the same time as bravery. There's a bit of a debate around battle synergy vs bravery, but they're kinda different. Battle synergy is purely defensive, and mostly good for tanking. If you can manage to keep your party close together (difficult with ranged+melee compositions) you can get a +20% defence and +12% damage reduction, which can be kinda handy. The upgrades are terrible though, unless you have a tank you can suicide for your companions (threat transfer+damage transfer = rather hasty death).
Rally is a great buff - It increases stamina/mana regeneration of your entire party (so your mages don't run out) and can temporarily transfer the might/control/defensive sustains to the party. Having one warrior with rally an upgraded control (+10% crit chance) and another an upgraded might (+10% damage, +25% critical damage) is a particularly effective combo. I'm selfish though, so I usually leave the job of buffing to my companions, so I personally wouldn't get rally for hawke.
Second wind is pretty much a stamina potion.
Bolster supposedly can be amazing at regaining stamina, but I've never really used it. I mostly just rely on killing enemies for stamina.
Hope this helps.