Sluff Coat
From AmtWiki
A medieval style overcoat, very popular in Amtgard, and notorious for obsfucating whether a shot hit someone or merely hit garb. Hence the name.
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. Usually includes a large back applique or other embellishment.