Every time a system user executes a skill his or her body enters calibration. Skill locking was the term used to describe this event. For this short period, the system forced the user to stand still to allow the body to recover from exerting itself.
The system told Hiro this defensive feature forced users not to solely depend on skills and practice actual tactical planning and combat maneuvers. But in the current landscape of Valorious. Duels became the primary means of settling arguments and even wars.
What good would challenge a kingdom with a high-level system user like Rhyne or her husbands? No matter how many men you throw they will all die meaninglessly before such overwhelming power. However, that only held true when one fought against normal people.
Monsters, bandits, and assassins for example didn't follow such conventions. Some even attempted to exploit this skill-locking mechanic, and it became known in the underworld as the Stupor window.
