@Aiox - Not sure yet, because I haven't started playing as Thief. I've levelled Warrior, Bard, Cleric and Magician so far. Thief is next, but I have to run out to do my weekly shopping shortly. Xd
Oh well, since you asked. Thieves can equip two weapons! I didn't have any daggers on hand, so here I have a sword and a mace. This is a serious DPS class, but... takes a lot of damage, so have a Warrior and Cleric on hand to tank.