There's literally no explanation for binding vows. Other than that, making binding vows with yourself can boost your powers, and the consequences of doing such a thing are light cause you only lose what you gain. For example, Nanami using his full power before Overtime would only mean losing the boost overtime gives him. Hell in JJK 0 Yuta and Rika make a binding vow to sacrifice their own lives to gain enough power to defeat Geto, but Yuta just breaks it by not going with Rika into the afterlife. Unlike Hxh where for example Kurapika would die if he used any of his anti-troupe techs against a non-member of the Phantom Troupe. Second is that binding vows between sorcerers/curses are different and can carry huge consequences, what are these consequences? We have no clue.