Not sure if this has been mentioned but i was under the impression you could only block with duel handed and shields, but in this screen the pc appears to be putting one hand over the other and angling the blade inwards as to be blocking.
http://pcmedia.ign.com/pc/image/article/116/1162158/the-elder-scrolls-v-skyrim-20110415033042643.jpg
You can block with weapon and shield, two-handed weapons, dual wielded weapons, and one-handed weapons, so long as your second hand is free of any spells, etc. when you try and block with the one-handed weapon.
And yes I would agree that the pic is either the block position with a longsword, or its the beginning of a power/finishing move on the staggered Draugr directly in front of the Nord.