If you intend to let your Bladesingers face waves of small foes, it is advised to upgrade Blade Dance first, before other skills. Blade Dance allows the Bladesingers to kill off lesser foes before they reach melee range, to thin out the horde pressuring on your choke points. Remember, EACH bladesinger performs Blade Dance, so in reality, 6, 9, or 12 attacks are done depending on upgrade purchases.