I thought people aren't using tank stance anyway?

A buff to Blood Price would be nice - it was already a lackluster skill in HW - but Blood Price is actually a strong ability in huge trash pulls, it gives you tons of blood for Quietus so you have mana to spam DA Abyssal Drain for the selfheal.

A counter attack on a skill wich is locked behind tank stance would further buff DRK for huge trash pulls, but does nothing for boss fights, the area where the skill needs a buff. But as long as people aren't using tank stance anyway, what should that buff accomplish?

I think it should be a defense buff or selfheal, nobody will enter tank stance for a damage buff. More defense would also help in progression or in "oh shit" moments, situations where you use tank stance anyway.