Shield Bash ? I'm a berserker, i don't use shields.

I spent a few nights trying out the three weapon configurations. 2-hand, dual wield and 1H + Shield. I think all of my weapons are orange to me.

Seems like the best strategy is to carry a two-hander, two dual wields, and a sword and shield at all times. The true beauty of a berzerker is its variety. As party composition and targets change, you will need to adapt your weapon choice.

I'm with Kronx on this one, I always carry a full compliment of weapons to best suit the situation. If I'm MT and I'm grouped with an Assassin and Wizard, I'll use a shield. Why? Because the difference in my DPS from going 1h+shield to DW or 2H as compared to the overall DPS of the group is smaller, so I much prefer the added defense. Replace the Assassin and the Wizard with a Shaman and Coercer, and I'll go DW or 2h because that group makeup is lighter on DPS. I like DW for soloing normally, and if I'm grouped with a Guardian who is MT I use a nice, slow 2h because it's less likely to pull aggro with Bloodlust going.

Mazzus

There is a 2H blunt weapon you get for the Kregnok Legbreaker quest Help the Troll (or something like that). The stats on it aren't that great (as with most 2hers) but the damage is huge and the delay is over 3s. I'm working off memory but that is pretty close to what it is.
You won't find any weapon that is really fast but has abnormally high damage. In a given tier of weapon, if you have one weapon with 1.2 delay that does 5-15 damage and another weapon in the same tier that is 2.4s delay it will have ~ 10-30 damage on it. They seem to be pretty good at balancing that out.