What is a gay swordsman?

A humorous term denoting a penis.

Definition

While the terms refer to the penis, they also generally imply a rather well endowed penis, not just an average length/width penis. Swizzle Stick is also a reference to one whose penis is being well used.

Noteworthy: Swordsman can also be used to denote a person who not only has a large dick, but one who is a good lover.