Sluff Coat
From AmtWiki
A sluff coat is a fantasy-style overcoat, a very popular piece of garb in Amtgard. It's notorious for obfuscating whether a shot hit someone or merely hit garb, from which it gets its name.
In Amtgard
It is typically a sleeveless vest with side an back gores for fullness, or splits. It is often at least as long as the knees and can go as deep as the ankles. The collar is almost always absent, and they often lack closures. It usually includes a large back applique or other embellishment.