If you hold shift, and hold your mouse button between your own feet (more or less, keeping your left mouse button in), you will take up a defensive stance.
This really does improve your defencive values, and is therefor not just graphically a blocking stance.
first: normal stance

Then, holding the left mouse button + shift, while pointing at your own feet

ps: sorry for quality, they are fairly big pics, so had them loose some quality for uploading's sake




















