>>717952946Blade Dancer by itself is pretty strong, but not OP, unless you play as a Death World Psyker. Kibellah is top tier when you get her in chapter 1, Blood Oath gives you 3 MP every time you use it if you have the Blood Rush talent, meaning that you can run from enemy to enemy and kill everything on screen. The fact that Death From Above doesn't one shot enemies is actually a blessing in desguise, because killing enemies with it doesn't restore charges, if you then kill a group of enemies who have been weakened by Death From Above with Blade Dance you suddenly get a bunch of charges of Death From Above, giving you even more mobility.
The problems with Blade Dancer arise when you get to Executioner, because you can use your ton of attacks per round to stack DoTs sky high, scale Wounds off of Medicae, and apply debuffs on enemies based on the types of DoTs they have. So you have a class combo with high mobility, high damage, high HP, high Dodge and debuffs.