Thanks. :) Is the slash going from his right to his left or his left to his right?
This is the part of written combat where your RL training could help immensely. Being able to picture a situation (or even get up and acually act it out) can help you be able to give as much detail as possible, making each attack or defense that much more effective. Essentially, the more detail you put into an attack, the harder it is for your opponent to do something unexpected that you didn't account for. Take chess as an example. If you just wrote "I move my piece", then that could mean anything and your opponent could make up just about any scenario to counter it. If you wrote "I move my piece four squares", it's a little bit harder for them to make anything up, but still heavily in their favor. If, however, you write "I move my rook to A-7, putting the king in check" there's only a handful of moves they can make to get out of it, and you can account for most (if not all) of them and plan accordingly.
Of course, there's always the hassle of getting them into the position where a check is possible, but that's the fun part. ;)