Here's an idea, since people are having trouble with the animations, why not make it an option to show a little indicator showing which direction the attack is coming from? Just like the "show attack direction" indicator, only it would show which direction to block instead.
Some people might oppose, saying this makes it "too easy", but I prefer broad playability on all levels over "Only l33t pr0s should be able to play this game and win". I mean come on, I fully expect a really good player without a shield to beat a noob with a shield, but as it is now, because the system is so clunky, that even your average newb can beat a good manual block user on many occasions.
Manual block should be easy to use, but difficult to master. It shouldn't be difficult because it is clunky and unreliable, but it instead it should be easy to use but hard to master. Right now its clunky and hard to use and its almost impossible to master.