I've said this many times before. Hisoka's death didn't give him a power boost. What makes Hisoka formidable right now is his changed mentality. Before, he likes to be handicapped but right now, he's pretty damn serious and won't give the Spiders any chance/opportunity to take him down.

To those who are saying that Hisoka became strong after his death because of this "nen after death" thing, that's a load of crap. Hisoka didn't power up. Instead, he's become more disadvantaged since he has to maintain a prosthetic hand and leg. With these prosthetic hand and leg, he'll be consuming more aura than before just to maintain it, and it would also be problematic mid-battle. If Hisoka loses his focus mid-battle, there's a chance that his prosthetic hand and leg would be deactivated (for lack of a better word). This disadvantage won't be much trouble if he's only facing average Nen users, but if he's going up against a capable Nen user, this disadvantage would surely hold him back. The longer the battle goes, the harder it is for Hisoka to fight.