Getting somewhere with Marozzo's dagger

I've been having some problems with Marozzo's dagger section, specifically Capitolo 54 & 57 dealing with the defence of the thrust.

The translation by Bill Wilson over at marozzo.org just isn't making sense, so I've been redoing it.

My main problem with Bill's translation is that the stated defence just doesn't work. Trying to stop a dagger thrust by cutting to the upper arm of the opponent doesn't give enough leverage, distance or force to stop the incoming thrust. The opponent just keeps going and I get stuck with the dagger every time. I had a look at it and I think the text is telling us to cut OVER the opponent's dagger arm, which when done to the lower arm does give us the leverage, distance and stopping force we need.

Marozzo Cap 54
Essendo in coda longa e stretta e ‘l tuo nimico ti tresse d’una ponta al pugno del pugnale, in trare di detta ponta tu alcierai la mano tua a l’insuso tanto che passi la ponta sua e a un tempo medesimo tu gli darai d’uno roverso traversato de sopra del suo braccio del pugnale;

My Translation
Being in coda lunga e stretta and your enemy thrusts at your dagger hand, as they make the thrust to which hand you will raise it up and the point will pass and in the same time you will give a roverso traversato over his dagger arm;

Marozzo Cap 57
Hora nota che essendo rimaso in coda longa e stretta e ‘l tuo nimico te cacciasse d’una ponta de sotto in suso con el pugnale suo, voglio che in uno medesimo tempo tu gli dia d’uno meggio roverso de sopra del suo braccio dritto;

My translation
Now note that continue being in coda lunga e stretta and your enemy thrusts forth with a rising thrust with his dagger at you, you shall at the same time give a meggio roverso over his right arm;

I wasn't sure I was on the right track, so I bounced it over to the guys on the 7 Hearts Forum, and it appears I'm on the right track! So it's a good day for me, and my uncertain plodding Italian skills!

Rick