Some first things that need to be established. I am not a physicist, I have not studied physics save for a little dabbling in Aristotelian Physics to greater understand Renaissance thought. So with this in mind my approach to using Heisenberg's Uncertainty Principle is going to be a little "popularist" and a little "generic". Please do not try to argue the physics of the situation, I am taking something from one field and applying it to another where I believe it fits. The inspiration for this came from watching a movie from another entirely different field, "The Catcher Was a Spy" in which the theory was used in a similar way to explain something not to do with physics.
"[Heisenberg's Uncertainty Principle] is any of a variety of mathematical inequalities asserting a fundamental limit to the precision with which the values for certain pairs of physical quantities of a particle, such as position, x, and momentum, p, can be predicted from initial conditions. Such variable pairs are known as complementary variables or canonically conjugate variables, and, depending on interpretation, the uncertainty principle limits to what extent such conjugate properties maintain their approximate meaning, as the mathematical framework of quantum physics does not support the notion of simultaneously well-defined conjugate properties expressed by a single value. The uncertainty principle implies that it is in general not possible to predict the value of a quantity with arbitrary certainty, even if all initial conditions are specified."
"I thought this was a fencing blog. What am I doing reading about physics?" This is probably what's going through your mind as you read the previous quote. The thing that needs noting about Heisenberg's Uncertainty Principle is that it can be applied to fields outside those of quantum mechanics and even physics. Or at least a certain basis of the Principle can be applied to these things. It is that last part which is most interesting, "it is in general not possible to predict the value of a quantity with arbitrary certainty, even if all initial conditions are specified."(https://en.wikipedia.org/wiki/Uncertainty_principle). Here, it is used as a "framing device".
In regard to fencing there are details given about techniques. These are based on the actions of what an opponent will do in response to the action of the fencer. Indeed, other actions are established on what the fencer is only able to do from that particular position.
Other techniques are detailed, these are based upon how a weapon will move. Others are founded on actions of the opponent. Some actions are established on the action of the fencer, intended to make the opponent move their weapon, thus produce the moving weapon.
Further admonitions assert, a fencer will act from a particular position in response to the action of the fencer and will move their weapon in a particular way. So prediction is made based upon both the position and the action. Indeed the same can be said that a fencer can be predicted to move in a particular way from a particular position with or without stimulus, according to what the texts teach us.
According to the Uncertainty Principle, none of this is possible. As it has been previously presented, such predictions cannot be made based upon such initial conditions when they are specified. A fencer may not execute the action predicted by the text, so the fencer has to respond in a different way. The fencer actually had no idea how an opponent will respond to any action they might make. All they can do is assess the probability of the response of the opponent.
The fencer must work on a probability matrix based on what they have observed of the opponent, but they can never be 100% sure of any action of the opponent, regardless of what information they have. Reading the opponent is vital in assessing this probability of what an opponent may do. The fencer should never be so sure that they think they know exactly what the opponent must do. The opponent always has options which are not planned for.
[Edited for clarity: 20/08/2020]