Why does the law of 'zealots may strike him' apply only during the act, and what distinguishes it from ordinary punishment?

This source-based Torah study examines the question: Why does the law of 'zealots may strike him' apply only during the act, and what distinguishes it from ordinary punishment? It follows the canonical Hebrew discussion through the weekly portion and the classical sources cited there, preserving the distinctions and review status of the original. This localized layer is for study and discovery only; it is not a practical halakhic, medical, legal, safety or pastoral ruling.