New player: about dual wield animations
Your 1-3 skills are affected by your main hand weapon. Your 4-5 skills are affected by your offhand. Every profession can dual weild
Dual wielding is a misnomer. What you probably heard of is that thieves are the only class that have dual attacks. That means that your 3 skill changes based on your offhand. Eg pistol whip is 3 skill for sword pistol, if you change your pistol to a dagger then you get flanking strike.
Every class who uses one handed weapons can have an additional piece of equipment on the offhand. Most are able to use dedicated off hands, that is, focus, war horn, shield. These generally have utility and defensive skills.
Some classes such as rangers, warriors, thieves are able to use weapons on their offhand. Warriors seem to be the best at this; they can equip swords, axes, maces in the offhand. Rangers can use axes and daggers. Thieves use daggers and pistols. Engineers can use pistols on offhand, necros and eles get to use daggers.
Gw2 is different from many other wow type mmos as the auto attack comes at an opportunity cost; using skills interrupts the auto attack and resets the chain. Offhand weapons do not auto attack, and are used primarily for the 4 and 5 skills they give you. Since you are a thief, your offhand affects your 3 skill as well so choosing an offhand weapon takes a bit more thought.
Hope that helped
Basha Blue – 80 Guard, Cat Harsis – 80 Ranger
And many more… on Crystal Desert Server (NA)