I think dual wielding owns single wielding even though single gives you 1 (depending on how many points you put in 2) AC bonus when you dual wield you attack a lot faster and enemies don't have as much time to hurt you. also there are a lot of AC bonus items. with my stalker i dual wield long swords/scimitars i chop enemies down very quicky, they don't get much of a chace to even think about hitting me back :D

You also get extra abilites when dual wielding. 2 weapons grant more helpful stuff than 1 weapon.

what do you mean extra abilites?

He means (If I'm correct that you get potential bonuses from both weapons. For example, if you're dual weilding Celestial Fury and, (off the top of my head) Arbanes Sword (short), you get both the stun effect of CF and the haste ability of Arbanes short sword.
Yep, dualling kicks some serious ass.

Both weapons function like they would if singlewielded.

Granted powers, such as ability increases and immunities work no matter what hand you are wielding the weapon with.

It should, however, be said that the far majority of your attacks will be made with the first weapons.

So if the weapon has a lot of cool abilities that function on impact that will better have to be your primary weapon.

Flail of the Ages with it's slow effect and it's many types of damages is a candidate for the primary hand while Crom Fayer with it's mighty strength increase is a candidate for the secondary hand (you might shift hands at times to enjoy Crom Fayer's golem slaying powers).