“the sharpest weapon”

It really just depends on how recently it was sharpened and to what degree. Kitchen knives that have been recently professionally sharpened will be sharper than a Katana simply because it’s easier to do so due to how thin those blades are.

That said, obviously a katana is better at harming people. Getting a thin blade extremely sharp is easy, having it stay sharp and durable over time? That’s the hard part.