As used in this article, unless the context requires a different meaning: “Ballistic knife” means any knife with a detachable blade that is propelled by a spring-operated mechanism. “Handgun” means any pistol or revolver or other firearm, except a machine gun, originally designed, made, and intended to fire a projectile by means of an explosion of a combustible material from one or more barrels when held in one hand. “Law-enforcement officer” means those individuals defined as a law-enforcement officer in § 9.1-101, law-enforcement agents of the armed forces of the United States and the Naval Criminal Investigative Service, and federal agents who are otherwise authorized to carry weapons by federal law. “Law-enforcement officer” also means any sworn full-time law-enforcement officer employed by a law-enforcement agency of the United States or any state or political subdivision thereof, whose duties are substantially similar to those set forth in § 9.1-101. “Lawfully admitted for permanent residence” means the status of having been lawfully accorded the privilege of residing permanently in the United States as an immigrant in accordance with the immigration laws, such status not having changed. “Personal knowledge” means knowledge of a fact that a person has himself gained through his own senses, or knowledge that was gained by a law-enforcement officer or prosecutor through the performance of his official duties. “Spring stick” means a spring-loaded metal stick activated by pushing a button that rapidly and forcefully telescopes the weapon to several times its original length.