The AI is almost always fooled by a player feint. You just have to make sure they're already blocking, then switch your direction quickly. The problem is, that there is no true feint button, so if you have a shield it no longer works. In which case the best feint i believe you can pull of is one in which you start the swing, then block, and switch direction very quickly and swing. Not quite as quick as using the switch shield button, but the best and only real alternative i think.