One of several giant armored knights found in the game. Even though he can be defeated easily by conventional means, his purpose in the game is a bit different. The intended way to defeat him is to force him off the ledge he's initially standing upon by making him retreat a little every time he's struck.
Once he falls over, the Gate Guarder will tumble down the slopes in the room and crash into a boulder at the bottom, destroying both it and the armor. This allows Juste to access the Merchant's shop in the next room.