I understand his thinking, but the way you wrote it just doesn't work. You can't respond to an attack that was never initiated (or even hinted at). That's just bad etiquette, and really not the way to conduct a duel. You can't just assume complete actions on the part of your opponent. If they've already made a move, then you can assume the results of that, but you can't just make up their next move out of the blue and expect them to roll with it when the move you expected is the one that would be the most beneficial to you. 

And putting the if statement at the end implies that everything prior to it was conditional. In the future, I'd recommend placing the if statement at the beginning of the conditional portion of your post, so as to make it clear which part it's referring to.

As for edits, I don't want to get into another long-winded debate so I'll just change mine.

Edit: post edited.