Like I said, while using a super(Like Nova Bomb) you take reduced damage. And Novabomb OHKOs almost anything unless its on the very edge of the blast radius. Your supers cancelled out, because you both do massive damage and take a sizeable amount of damage more than 2 basic melee hits to kill. Say health is 100hp, right? And a basic melee hit does 50 melee dmg(since it takes exactly 2 to kill any basic enemy)? Bladedancer does 100 melee damage(Since it 1-shots any basic enemy). And say the super buffs health by... 25%. So it takes 2 Bladedancer hits to take out the Voidwalker with 125 health, and his Novabomb, which probably does close to 200 damage, gets you with 75% because you're at the edge. Thats still 150 damage to your 125 health Super-ing Bladedancer. So you both die. Just another way to think about it I guess... I know the numbers are in the 300s and stuff but I simplified it anyways.

Still don't think they should be invincible. Gunslinger, my god, you know how many times I get shot twice by a handcanon and die while in the animation?