Then provides a kind of half-definition "Laws prevent injury, enslavement, and plunder" so implying that restricting the kinds of weapons one can carry can't prevent injury. However no argument is made as to why this might be true. No response is given when this is highlighted.
In response to the above statement: "restricting weapons cannot prevent injury." On the contrary, the very fact you're restricting them causes injury. What will happen is you will threaten or remove my ability to acquire (own) a "weapon" as opposed to the unjustifiable use against another (a legitimate claim). This force or threat of force causes injury in and of itself.
To wit, if I ignore your supposed "law" and acquire a weapon in opposition to your "law", your law gives you and yours the permission to punish me (inflict injury or enslavement) in an attempt to stop me. Law is force legalized (a simple distinction no doubt).
Restricting weapons causes injury. However, you intervening in a "fight" that uses a weapon to bring injury to another man and his property, could prevent injury. Simply speaking, you have no business in what physical characterstics my property has, for were that the case, property would cease to be property (exclusive ownership is not possible)
On the other hand, were you enterprising enough to acquire (and not thru theft/plunder) all of the materials to make said "weapons" then you could probably prevent injury. Have fun with that one though.