RCW 9.41.250Dangerous weapons — Penalty — Exemption for law enforcement officers.
(1) Every person who:
(a) Manufactures, sells, or disposes of or possesses any instrument or weapon of the kind usually known as slung shot, sand club, or metal knuckles, or spring blade knife
, or any knife the blade of which is automatically released by a spring mechanism
or other mechanical device, or any knife having a blade which opens, or falls, or is ejected into position by the force of gravity, or by an outward, downward, or centrifugal thrust or movement;
(b) Furtively carries with intent to conceal any dagger, dirk, pistol, or other dangerous weapon; or
(c) Uses any contrivance or device for suppressing the noise of any firearm,
is guilty of a gross misdemeanor punishable under chapter 9A.20