This next action really should have followed the first offense.
Or pretend to attack with a mandritto, but throw a riverso.
Ideally you abort the mandritto just before the blades clash. If they touch, and then you leave, your opponent will have a pretty good idea about what’s coming next.
The riverso itself can strike high or low depending on what looks more open.
If, however, he throws a mandritto, you will go with your sword into guardia di faccia. And when he turns a riverso at you, either high or low, you will ward it with your sword, immediately turning a mandritto at him in whatever way seems best to you.
We found this to be a really effective counter. Extending into Guardia di Faccia allows for a solid counter if the mandritto is real without drawing the blade so far out of line that you can’t parry the riverso.
After the second parry you may find your point between his blade and head. If so, awesome. Don’t leave that place, just turn a quick wrist cut into his ear with the true edge.
If instead you find your point high, flick the point up and off his blade. (The Germans call this a Zucken or pulling.) Then attack the flank or thigh while keeping the buckler high to protect your head.
Counter with Grappling
If he closes with you when attacking with the riverso, you have the opportunity to grapple. Parry the two cuts as above, then step forward while pushing your sword and buckler between his tools. The edge of your bucker will easily part his sword and buckler.
Then immediately envelope his sword arm using your buckler arm. You want to grab his arm or sword and arm. If you try to take his sword alone he will cut your flank under your arm before you gain control of it. As soon as you have his arm, cut or thrust to the nearest opening.
As you do this, be wary of his buckler. He may ignore is own defense to smash your face. Or worse, he may let go of his sword and punch you with the buckler without risk to himself.