First, if you are "123ing" you ARE doing it wrong.

Second, Dark Arts needs to be strategic and not just use it as much as possible and damn the consequences. Remember that a DA/Souleatter combo averages 266 potency which is one of the highest average potencies, just an example the new Dragoon combo of True Thrust -> Vorpal Thrust -> Full Thrust -> Wheeling Thrust only averages out to 250 potency. Having both Blood Weapon AND Blood Price, giving us pretty much endless MP, would end up being pretty overpowered.