I'm disappointed by Harold's need to use such a sword. Doesn't this basically mean it's a detail that was never revealed in the game? Harold was supposed to be an extremely difficult opponent for Liner's party, a mid boss, and neo-Harold based his expectations of Harold's level of power on that. Which is why he was driving himself so hard, to reach that level. Yet now it's revealed it was, to an unknown but clearly significant degree, thanks to a magic sword that expends the user's own life. In short, Harold never was as tough as the game made him look like.
But then again, these recent chapters did fool me once, by making Harold such a master actor that I assumed, against the clear evidence, that El is not Giffelt. So, I'm willing to also bet that Harold actually has no use for the sword (meaning Giffelt is wrong) and he only used the sword here to give Giffelt wrong information. So, maybe he lost a week from his life expectancy. Elsewhere he would just be dragging the cursed sword along, without using it, relying on his own power.
I mean, Harold's life was to be spared, after the corrupt judgement, if he served Justus, so it would be pretty pointless to voluntarily throw away that same life of his by using a self-leech sword. It would be like asking him to choose between two death sentences. Not much of an incentive.
I wish this was enough of an edgelord story for Harold to go and deal with the corrupt deliberation council on his spare time.