noun
A small concealed dagger carried inside the kimono, historically used for self-defense or ritual suicide.
武士は懐刀を帯びていた。
The samurai carried a dagger inside his kimono.
noun
Figurative use; refers to a trusted advisor or indispensable aide, often in political or organizational contexts.
彼は社長の懐刀として知られている。
He is known as the president's right-hand man.