Personally I only use a shield as a Warrior on raid mobs when defensive discs are all used up and/or out of endurance, and a few other times. Dual Wielding is the way to go in general as the main tank warrior, as you get faster swings and more procs to help with aggro which is generally the key factor. Also with AAs such as
Slippery Attacks that reduce enemy ripostes of offhand attacks completely when maxed leveling out the main reason to use a 2H (other than the riposte disciple). I generally save 2Hers for when I'm not main tank, but you can also tank with a 2Her, it will likely be slightly tougher (but not by alot with good procs and low delay and good ratio) to keep aggro.
Most would say in general fights not to use the shield as a War, for the loss in aggro, dps, and since group mobs aren't that tough. Personally, I try to keep Anger and Enraging Blow proc augs in my dual wielding weapons, and low aggro / dps procs, in my 2Her and just use dual wielding the majority of the time, and 2Her when playing a dps ('cough) or assist role, and the shield as I mentioned only versus very hard hitting raid mobs. Just to clarify, I'm not saying using a shield isn't great, but rather is just not required for most fights.
EDIT: By far SKs are the best soloers, and also have the best AE aggro of the tanks, along with a nice line of spells that make them very versatile, and incredible soloers at higher levels when they can life tap from weapon damage. Warriors are best versus single hard hitting mobs. Paladins of course rule against undead. With a merc though, all will do fine. See
this thread for a good comparison of all the plate classes.
Yther Ore.
Edited, Jul 12th 2011 4:12pm by Yther