Hunter x Hunter Nen Ability Concept: 'Vow and Constraint' (Spoilers Included)

I recall 'Vow and Constraint' only appearing for two characters in the TV version. The first is Gon. When facing Neferpitou, he vowed that if he could defeat her, he'd be willing to lose anything. This vow's price, 'I don't care what I lose,' granted him immense power. This strength made Neferpitou, who had previously defeated Kite with a smile, feel fear for the first time. She thought this power could defeat Meruem (the Ant King). However, the Ant King grew stronger after his rebirth, so it's unclear who would win between this ability and the evolved Ant King. The second is Kurapika. His abilities are five in total, corresponding to his five fingers. When his eyes turn scarlet, he becomes a specialist, allowing him to utilize Nen abilities from all categories. To defeat the Phantom Troupe, he felt this power wasn't enough. He made a vow that this power could only be used against the Phantom Troupe; using it on others might shorten his lifespan (?). This greatly enhanced his Nen abilities. However, Hunter x Hunter emphasizes equivalent exchange: the greater your price, the greater your power. Clearly, his ability isn't as strong as Gon's, but his survival rate is higher. His vow and constraint involve the 'Binding Chain' on his middle finger, which prevents Phantom Troupe members he binds from using Nen (putting them in 'Zetsu' state) and immobilizes them. Using it on others would result in immediate death by the 'Judgment Chain' on his pinky finger. In his first fight, he single-handedly defeated Uvogin. He also had the ability to hold the leader (Chrollo) hostage (holding the leader hostage doesn't necessarily mean he's stronger, as Chrollo's ability requires 'planning' to fully utilize his 'Book of Secrets' ability). As a side note, after Chrollo used his ability on Chiyou, she died a few months later. His teammates jokingly called it the 'Death Note.' I found this part hilarious, it's a great gag. But thinking about it,