Are brass knuckles legal in Maryland?

Answer 1

In Washington they are illegal;

RCW 9.41.250

Dangerous weapons -- Penalty.

Every person who:

(1) 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;

(2) Furtively carries with intent to conceal any dagger, dirk, pistol, or other dangerous weapon; or

(3) Uses any contrivance or device for suppressing the noise of any firearm,

is guilty of a gross misdemeanor punishable under chapter 9A.20 RCW.

Answer 2

Yes, but you cannot carry them concealed nor use them against another person in a malicious manner (including threats).