Weapon
A weapon is a tool used in combat, and used offensively or defensively as an aid in defending oneself or one's group from or attacking another.
Weapons can range from simple clubs and sticks to assault rifles, tanks, and aircraft carriers.
Humans have invented more sophisticated and powerful weapons over the years, to the point where several countries now possess nuclear weapons and can annihilate millions of people if necessary. It was thought at one time that advanced weaponry such as machine guns and atom bombs would make war obsolete, but they didn't.