This line/philosophy unlocks the Leichtenhauer system when it is fully understood. Longsword fighting traditions rely heavily on body and sword mechanics. Understanding the principals of those mechanics is absolutely key to beginning to understand the fighting system as an entire system.
First, some key concepts
The Basic Principle
If he commits to an action with strength- recognize what he is doing, and give-in (show weakness). In giving-in however, transform his strong commitment to his action into an opening, and attack it.
If he shows weakness in an action, a bind for example, push through that weakness, and transform it into an opening.
The Sword’s Three Axis
Edge: The first is the edge axis which aligns with the edge and the cross. When swinging the sword with the intention of cutting, the blade is traveling along its edge axis.
Flat: The second is the flat axis and describes the flat part of the sword’s blade. The blade travels through its flat axis on some blocks and parries.
Length: The third axis is the length and runs right down the center of the blade from the point to the pommel. A sword travels along its length axis when thrusting with the point.
Generally, strength is applied to either the long axis in a thrust with point or pommel, or the edge axis in a strike or cut. The flat axis is usually only used in a bind situation.
Lever and Fulcrum: If the sword is a lever, and the grip is the fulcrum, then simple physics tells us the the farther along the length of the lever that force is applied, the easier it is to move the lever by forcing the fulcrum to pivot.
Skeletal//Muscular Alignment & The Cross
Imagine the position of your body when you do any strenuous, strength activity. Push starting a car for example: you push with all of your muscle groups and joints aligned, and working as one. You must coordinate your stepping motion and body alignment to maximize your power.
Your body has aspects to it that are strong and weak. Imagine pushing the car again. You are incredibly strong along your forward/backward axis during the exertion, but you would fall right over if any perpendicular force were applied to you.
If these two axis were viewed as straight lines, they would form a cross. Always remember how enchanted with cross imagery the medieval mind was. These elements were included into their daily philosophies as much as possible.
These strong and weak aspects are always with you- and your opponent. Whenever your opponent is strong, there is always a corresponding weakness. Often, the location of the weakness is in some way perpendicular to the strength. All you have to do is find it!
The Standard Sword Grip: Along the axis of the sword in line with the arm bones is found the strong of the sword. In the standard grip this is referring to the lowest half of the sword edge pointing away from you. This is referred to as the long edge. The upper half of the long edge is referred to as the weak part of the sword because it is more easily levered. The physics of the inside, or short edge, are identical to the outside, but the short edge is weaker, in general, than the long edge. When the sword is swung in this grip, the edge is aligned and powered with the top of the wrist pushing forward. This motion is the most powerful.
The Thumb Grip: This grip is adopted when the sword is twisted 90º in the hands from the standard grip, and the thumb placed along the blade. This grip retains both long, and short edges, but they are much weaker than in the standard grip. When the sword is swung in this grip, the edge is aligned and powered with the top of the wrist rotating with a windshield-wiper motion.
Grip Strength: When the sword is held in the hands in either fighting grip, it has a strong and a weak aspect. To simplify, imagine holding a sword in front of you in the standard grip. The grip is strongest along its edge axis, and very weak along its flat axis.
Putting It Together: Some examples . . .
Go back to the line, “Meet weakness with strength, and strength with weakness.”
Three of the Master Strikes (krumphau, zwerchau and scheilhau) depend of these principals in a very interesting way. The strikes meet the strength of an oncoming edge, by attacking and displacing it on the perpendicular: on its weak, flat axis. Once the foe’s blade is set aside in this way, the master strike transforms (winds) around the sword’s long axis in some way, and becomes an offensive strike that comes from an angle that is difficult to counter- hence the name “master strike.”
Taking off at the sword (Abnehmen) also makes interesting use of these principals. In a bind, if your foe is pressing hard against your blade with outward pressure, then take off. The sudden lack of counter-pressure against his sword causes him to fly outward, and creates openings all along his opposite side. Meet strength with weakness.