Gangster's Blade is a term used to describe a type of weapon, usually a knife, that is associated with gangsters and criminals. The term is often used in crosswords, and the solution for this particular clue is SHIV, a four-letter word. A shiv is a homemade knife or blade that is often used as a weapon by criminals. It is typically made from a sharpened piece of metal or other material, such as a broken bottle or a razor blade.