If your holding the sword and just hit your attack button it'll start a three attack combo, if you hold it down you lunge. Everybody knows this part.
If you hold block a few extra mechanics are added.
You can dodge jump by holding a direction and hitting jump.
Your main attack combo is altered slightly with the first attack slightly increasing move speed.
While blocking, if you start a power attack, you move a normal run speed the entire time you are charging up the power attack, you can jump and everything.
When you aren't attacking you block sword attacks from the from. Though this is one is obvious.
This should probably be pointed out in game or something, I see a lot of people on the forums talking about how the sword mechanics should have more depth. A parry, dodge, and counter attack mechanic added to it.
Its there, its just not obvious.
