So, from what I can tell, it looks like the left side of the block tree is for a shield, and the right applies to both shield and weapon blocks. However, I am still afraid to invest perks into shield wall just in case it does nothing. Can someone at Beth confirm this, or can someone tweet someone at Beth?

http://elderscrolls.wikia.com/wiki/Block_%28Skyrim%29

This page has a list of block perks, and tells you which affect 2 handed weapon blocking.

:thumbsup: