Kogatana

The Kogatana is one of Juracule Mihawk's weapons. It's an dagger cross pendant worn on his neck. Mihawk says he uses this weapon only to defeat weaklings. In fact, is more an accesory than a weapon. Though it appears to have no value, in the hands of Mihawk, it was able to defeat Zoro with the slightest bit of pressure, and was able to stab close to his heart.

Trivia

 * In the 4Kids dub, Kogatana's cross shaped sheath was edited out.
 * Although it's name was never revealed in the manga or anime or databooks, in every game where this weapon appears this name.