a sword, specifically a short sword or dagger: the physical weapon, and by extension the killing, the lawful force, the war, and the piercing power that a sword stands for
At its core this is the ordinary word for a sword, and in most places it means exactly that: a short blade drawn, carried, or struck with. It was not a long broadsword but a shorter weapon, the kind a person kept at the side for close fighting or self-defense. Nearly every occurrence in the arrest of Jesus is this plain, literal weapon.
From that concrete picture the word reaches naturally into figurative uses, the same way English speakers say someone "lived by the sword." It becomes shorthand for a violent death or an execution, so that to be killed "by the sword" simply means to be put to death. It can stand for the coercive power the state carries, the authority to punish wrongdoers. And it can name war itself, or the deadly danger and division that violence brings.
At its furthest reach the word turns into a vivid image for something that cuts and pierces without being metal at all: the word of God, described as sharper than any two-edged blade, and "the sword of the Spirit." The single thread running through all of this is a sharp instrument that divides and kills; each sense is a step out from that one picture, so they belong together as one word rather than as unrelated meanings.