No-one seems to want to answer you, so I`ll do it;
DFA was extremely powerful in the 1.02 version, but has been severely reduced in effectiveness now. It can still be a one-hit kill if your opponent is unaware though. Besides, it looks good.
The basic move is this:
Using the Red (heavy) stance, press and hold fire. When the sabre is right back over your head and about to come back down, press forward and jump. If you do it right you`ll leap forwards without somersaulting and end up kind of kneeling on the ground.
You can do this move from a run or a jump with practice. The most important thing is not to hit jump too early. You can afford to leave it very late and still get the move right.
The problem with DFA now is that it has a very slow recovery time and most people can see it coming a mile off and simply dodge and counter.