It can be noticed that there is no difference in damage from Quick Slash lvl 1 and QS lvl 2.
On level 1 the skill dealt ~75% of Auto Atack damage. As discription says second level of the skill should double it's damage. Unfortunatelly after buying the upgrade damage from the skill did not change (still ~75% od Auto Atack damage)
Tested for 1 minute, 2 tries each (one before and one after buying the upgrade).
It can be noticed that there is no difference in damage from Quick Slash lvl 1 and QS lvl 2. On level 1 the skill dealt ~75% of Auto Atack damage. As discription says second level of the skill should double it's damage. Unfortunatelly after buying the upgrade damage from the skill did not change (still ~75% od Auto Atack damage)
Tested for 1 minute, 2 tries each (one before and one after buying the upgrade).