The essential cognitive skill behind the application of swordsmanship is to see what is really there, not what you think is there. This is a profound and difficult skill to master, as we are all subject to all sorts of cognitive illusions and biases. Daniel Kahneman’s Thinking, Fast and Slow is perhaps the best single resource on the subject.
For us, in practice, we have to pay attention to what the opponent is doing, all the time- but refrain from telling ourselves stories about what we see. “His sword is coming towards me” is meaningful. But “he is attacking” is not: it prevents us from realising his action may be a feint. Ascribing motives to his motions is to be avoided. Likewise, we must not tell ourselves stories about what we are doing. “I am parrying that attack” is a lie. Because you don’t know whether the parry will work, or whether the attack is real, or anything. “I am moving to intercept his motion” is better, because the movement is real, and its intention is clear, and if the interception fails to occur, there is nothing in that statement to prevent the motion changing to find his weapon.
If we are telling ourselves a story, and the action changes, rewriting the story to fit the new data is hard. So we tend to ignore the data that doesn’t fit- we prioritise the story over the facts. This is normal. But will get you hit. I don’t think we can truly prevent the story-writing process, but we can cast the story in terms that permit endless easy rewrites as the situation changes.
Of course, the fight happens faster than conscious thought can keep up. Which makes story-telling that much worse, as the data is not just incomplete, it’s out of date. Better then to give yourself a set of instructions that fit the goals of the bout, such as “control his sword and hit him”, and let your training do all the hard work of actually issuing specific commands to the sword.
My own solution to the distractions of the conscious mind when fencing is I quietly sing a little song to myself. That keeps my conscious story-telling mind gently occupied, leaving my adaptive unconscious relatively unfettered, and able to see what is happening. It also freaks the hell out of my opponent if they get close enough to hear it. A win-win situation.