My weapon of choice would be the Gae Bolga, a magical sword wielded by the Welsh hero Cuchalain, which would explode into hundreds of little metal hooks and barbs when it struck a foe to tear up their insides. No doubt it would be fatal and excruciatingly painful. Or, if we're talking about realistic weapons, I'd probably use some sort of dart gun with the darts coated/filled with a specially engineered super virus that could not be cured, was not contagious (I don't really wanna cause a pandemic; too much collateral damage), and made its victim die in mindblowing agony. The victim would either be a personal enemy of mine who you do not know and as such I see no reason to name, or whoever's in charge of Cartoon Network these days. I'll show THEM to mess with my shows!