It is no coincidence that this bears a resemblance to the first assault of Marozzo, as they share the same tradition and it is quite possible that Antonio Manciolino and Achille Marozzo even shared the same teacher.
The quoted portions are from the W. Jherek Swanger translation of Opera Nova.
Assault 1 Part 1
1. Coda Longa e Larga
Firstly, opposite your enemy, you will place yourself at one end of the hall or of some other spacious field, arranging your body over your legs, and your sword and buckler in your hands, in such a manner that each movement, each act, each gesture is full of grace.
While any guard could theoretically be used, I am choosing Marozzo’s first position, Coda Longa e Larga, to start this assault.
2. Pass right and falso to the buckler into Guardia Alta
And wanting to come towards your enemy, you will pass diagonally toward your right side with your right foot, and in such passage you will give a blow with your false edge to the dome of your buckler, putting your sword into guardia alta, and your buckler must lie toward your face in the manner of a mirror,
Note that Manciolino’s Alta is with the point back.
3. Pass left and falso to the buckler into Guardia di Testa
and passing forward thereafter with your left foot, you will touch your buckler again, arranging your sword into guardia di testa,
4. Step right into Guardia Alta
the buckler falling along your left thigh, and then you will step forward with your right foot, lifting your sword into guardia alta,
Notice that he doesn’t touch the buckler this time.
5. Pass left with two cuts into Guardia di Testa
and then passing with your left foot you will do a montante followed by an over-arm mandritto <i.e. a mandritto that goes over your own left arm>. Then you will go with your sword into guardia di testa,
I believe the translation is supposed to read “a montante following by an over-arm mandritto” as it doesn’t make sense to throw a rising cut from Alta. Furthermore, in the section on Guardia Alta the author explicitly says that you can throw a mandritto followed by a montante.
6. Step right with a falso to the buckler into Guardia Alta
and stepping forward with your right foot you will touch the dome of your buckler with the false edge, and you will do a montante that rises into guardia alta,
7. Advancing Step with a Fendente back into Guardia Alta
and after that you will embellish the play, which is done by sending forth first your right foot, then your left, and cutting the edge of your buckler with a fendente so that having done this the sword must fall and immediately reascend to the rear into guardia alta.
This is the first non-passing step in the sequence.
8. Pass left and falso to the buckler into Guardia Testa
And drawing your left foot near your right, you will subsequently retouch your buckler and then you will step forward with your left foot into large pace, replacing your sword into guardia di testa.
This is the first time we touched the buckler from Alta.
9. Pass right and falso to the buckler into Guardia Alta
Then, passing forward similarly with your right, you will hit the dome with a falso, and do a montante into guardia alta, throwing your right foot alongside your left, so that the buckler guards your head well, and thus far to this point is contained the fashion whereby you must come to find your enemy. And do not forget, reader, such embellishment of play, because in more places in the present assault we will refer to it without redescribing it.
The Alta in step 4 has an explicitly lowered buckler to make room for the cut that will immediately follow. This alta seems to have a high buckler, suggesting that its location is very much contextual.
It seems the purpose of this sequence is to focus on the transitions between the high guards. Touching the buckler forces the point on-line, which is useful for both thrusts and quick cuts to the face. (Plus its loud and showy.)