What is the origin of the idiom "armed to the teeth" and when to use it?

The idiom "armed to the teeth" likely originated from the image of someone being so heavily armed that they have weapons in their hands, on their belt, in holsters, and even in their mouth. It is used to describe a person or group that is excessively or overwhelmingly armed with weapons, often to emphasize their readiness for a confrontation or battle.