In ancient China, civilians could possess knives but were strictly prohibited from privately keeping armor. On the surface, knives are offensive tools, while armor is defensive, but the focus of the system is not on "whether it can harm others," but on whether it can reduce the costs of being governed or controlled. Although knives are aggressive, their risk is "limited and controllable": a person holding a knife can still be easily subdued, and the power structure would not be fundamentally shaken because of it. In contrast, armor fundamentally enhances survival ability, making it more difficult for individuals to be quickly suppressed in conflicts, thereby significantly increasing the capacity for resistance, opposition, and even organized rebellion to persist.

In other words, armor lowers the "cost of control" and increases the "probability of losing control." From a system design perspective, this tendency is not limited to ancient times. For example, modern society also often follows similar logic: not all "attack capabilities" are strictly restricted, but those that can significantly enhance "resistance ability," "resilience," or "ability to oppose systemic suppression" are often managed more cautiously. Essentially, this reflects a governance priority: it is not about preventing individuals from "hurting others," but about preventing individuals from being "difficult to constrain."