With barbarians do you use a shield to make up for the lack of metal armour, or do you dual-wield to make sure you do a lot of damage?

I go for double-handed swords, personally. That, or a nice axe and shield combo.

Double handed swords or axes for me. Sometimes it's a flail and an axe, but thats only on rare occasions :)

Axes and Shield to start, eventually building up Dual Weilding.

I find that doing the Copper Coronet early and buying that throwing axe that's sold there helps a ton in the early game, but dual weilding with Belm or the Equalizer is great later on. I love the Axe you find in the DeArnise keep. If nobody else uses it, I'll use the Flail of Ages instead.