The stats listed below for mana cost are the true values and does not represent what is shown in-game.
A Barbarian warrior learns to fight with a weapon in each hand, for after all, are not two weapons better than one? A young Barbarian learns to use both hands independently of each other, striking simultaneous blows at separate targets. As his talent grows in this skill, he attacks with increasing control and accuracy. 
↑Diablo II Manual, page 63. Blizzard Entertainment, 2000.