Battle Stance is a flexible stance that is most suitable for young leveling Warriors and PvE DPS Warriors.
Abilities usable only in Battle Stance: Charge(unless the Warrior has the Warbringer talent in the Protection tree), Overpower and Retaliation. However, Battle Stance shares many further Warrior Abilities with the other two Stances, making it a very flexible stance for general use. Battle Stance is especially useful in PvP for Warriors (though this benefit is negated for Protection Warriors with the Warbringer talent.)