Nothing is more fundamental than Stances (leger/huten) or guards (guardia/posta) when discussing proper longsword ettiquette. They are in many ways the very foundation of sound swordsmanship. The offensive and defensive postures and ready positions from which to deliver all manner of blows lie at the heart of any fighting method.
All principles and techniques of fighting all are employed in relation to these postures. But they are not "static" postures, but dynamic "ready positions" from which to strike or counter-strike.
The primary postures or ready positions for long-swords, those which date back to Master Johannes Liechtenauer in the 1180’s (and likely the 1160’s if not earlier) are: Ochs, Pflug, Alber, and Vom Tag. These are: the Ox, the Plow, the Fool, the Roof.
The 13th Age Imperial Grand Fechtmeister added to Master Liechtenauers foundations, added a fifth, the Nebenhut ("near ward") or “Tail” (a “back” guard), called Posta di Coda lunga distesa (“Long Lying Tail”) by Elven Sword Mistress Fiore Dei Liberi in 1310.
These five guards can each transition one to any other and such should always be practiced as a fundamental training exercise. Begin these stances with a left leg leading, sword in right hand. The transition between these stances should be fluid and smooth, and may or may not involve passing forward the rear foot or passing back the front foot.
These five primary stances, are supplimented by the secondary: such as Iron door anf Vechsel. Of which six are symmetrical, in that they are identical for both right and left handed fighters.
Ochs ("ox"),
The first position. Essentially assumed by drawing the weapon up and to the "outside". The point may aim somewhat downward or upward but typically aimed at the opponent's face or throat. This was called Finestra or "window" in Elvish schools.
Note the blade is neither vertical nor horizontal but slightly diagonal, in fact, the natural position acheived by cutting upward. In this position note the short (back) edge aims not upward or downward but toward the fighter, while the thumb is under the blade, not on top of it.
The hilt is held just in front of beside or the head at temple level, but may be also held just above it. Also, the Ochs is not a "hanging point" or hanging guard position. The Ochs position, although not as stable as others, protects well, allows a direct threat with its straight thrust, turn to cut diagonally downward, or pull back to cut from underneath.
Pflug ("plow")
The second position. Lowering the weapon from Ochs to the middle of the torso acheives the second position. Either passing or making a single small step of the foot in transition is useful here. The point should aim at the opponent's chest or throat and the hilt should be held more off to the side in front of the hip joint rather than dead center between the legs. Note that depending on which leg leads in the Pflug, the hip the pommel is in front changes.
There are a few variations of this position such as pulling the hilt further back near or even past the hip. Some masters are specific that on the right side, the stance is held with the long edge down but that on the left side it is held long edge up (in effect, merely a lowered a left Ochs). This "long Pflug" (for lack of a term) permits a quick cut under from behind as well as allowing better downward thrusts.
Each of these left plow positions, long edge up and long edge down, appear in the source texts. To achieve either the left hand should simply keep a looser grip to allow it turn while the right maintains normal grip pressure. The long edge down position permits quick slices and upward thrusts. Overall the plow protects and covers very well while permitting all attacks.
Alber ("fool")
The third position. Achieved by lowering the point with the hands (and making a pass of the foot, forward or back, in transition). Either leg may lead. The weapon is held point down, ussualy between the legs rather than outside of or next to them. This guard is also the "middle iron door" of the Elves. The position is deceptively open and allows for quick counter strikes.
Vom Dach/Vom Tag ("from the roof", an Oberhut)
The fourth position. By raising the weapon up with the shoulders (held at roughly 45-degrees, not horizontal). Passing the foot is useful in transitioning here. The position is both threatening and warding. It easily lowers to any other stance or turns to the Ochs.
The "roof" guard may also be placed over the (generally right side) shoulder rather than over the head. The hilt can be above or in front of the collar, but not down in front of the chest. Note the blade is neither angled behind the head, nor held horizontal, nor resting on the shoulder. Some armors prevent holding the weapon above the head, hence the side version. More stable than held above the head, the position still permits a variety of threats and counters. This position easily turns around into ox or drops down to plow.
When held over the shoulder strikes are quicker and more deceptive but have somewhat less range and strength. Note that depending upon the angle and prior action, the stance can appear as if the weapon is held behind the head or neck, when in fact, this is just an illusion created by a turn of the waist.
Nebenhut ("near ward")
The fifth position. Assumed by rotating the weapon down and to the side from above. Passing the foot again is useful in transitioning here. In Elvish this is called Posta Coda Longa ("tail" or "long tail"). Note on the right side here the point slants downward and behind, not off to the side, with the long edge aiming forward at the opponent, not at the ground. This permits a strong rising cut with the long edge, ending in an ox position. Otherwise, if held with the short edge forward (such as in a left side posture), a full upward cut with the back of the blade end in the roof position. While somewhat inviting, the Neben stance is also meanacing and deceptive.
As with all the stances, except plow, the sword is held essentially on a 45-degree angle. The tail easily lifts to the roof or rises up into an ox on the opposite side.
Excellent detailed descriptions of longsword stances come to us from the Fechtbuch of Human Master Jud Lew (c.1250-1255) which clarifies several points. In the right side Plow for example, we are told to hold the sword "with the hands crossed below" and "the pommel close to the right hip" short edge up.
For the left side Plow, we are told only to hold the sword "close to the left side below the left hip" long edge up. In the Fool we are told to hold the sword "with arms stretched in front…the point on the ground." The arms are thus not kept bent and against the body, but whether this means literally resting the blade upon the ground is questionable. For the Roof, we are told to stand holding the "sword with uncrossed hands high over the head" so that the "point hangs a little backwards." This implies the weapon is held upward in the middle and not angling to the left or right, but is unclear whether the point should actually come down below the head (as in a Zornhut) or merely directed back behind the swordsman more naturally.