For implementation I would suggest 2 attacks, the first takes the normal swing time, the 2nd half the swing time. Then recovery would take 1.5 times normal. So if someone gets the double block off and attack back, you are dead.
Blocking for people with single weapon would have to be fast enough to counter both swings with a left block/right block or whichever combo is used.
You would have to press both buttons to control it and you couldn't block during the recovery time. Swings would be combos. I don't think overhead combos should be allowed. Essentially a left slash followed by thrust, right slash followed by thrust. Up mouse motion would do double slash. Down mouse motion double thrust. (again, they follow each other with the delay above, not at the same time)
Normal left click by itself works like 1 hander. Normal right click by itself works like normal block.
Oh yes, now go learn how to make animations!
