This play is taken from the play of the dagger. That is, the first dagger remedy master puts his left hand under the dagger to strip the dagger from the hand. In the same way, this scholar puts his left hand under the right hand of the player to take the sword from his hand. Or, he can put it in the middle bind as shown two plays after the first dagger remedy master previously mentioned. And that bind is done by this scholar.
Although presented as a large number of individual plays, armizare is more realistically seen as a collection of principles which can be applied with different weapons and under slightly different circumstances. This is an excellent example of the cross referenced nature of armizare. Fiore makes it very plain that you are applying a dagger play in the context of a double handed sword.
From the crossing of the 3rd master, push your left hip forward and let go of the sword with your left hand. Keep your fingers together, but extended, and your thumb tucked in. With your hand in a vertical plane, tip your fingers down slightly, ensuring a straight line from the mid knuckle of your thumb, along the back of the hand, and down the forearm.
Use the pivot of your hips to slice your left hand up and forward. Step through with your left foot as you do so. Your hand should slide through the gap between your opponents right hand and the sword handle. Keep your fingers together and your thumbs tucked in , or they will catch, tangle, and potentially break on something on the way through. Contact your opponent with the top of your wrist. To find the target, your hand needs to move in a straight line, inserting itself in place.
Use the twist and step to bring your right hand up to posta di fenestra. This is the moment pictured.
One way to continue is to roll the fingers of your left hand up and over your opponents forearm. Grab the wrist and pull your elbow back to your core, rolling your hand in an anticlockwise spiral as you bring it in. Turn your hips back as you do so. With your forearm levering on the sword hilt, the blade will tip to the outside line, while also pulling your opponent off balance.
You already have your sword pointed directly at your opponents face. This will give a clear path to push it into them as they fall forward.
A second way to continue is to roll the fingers of your left hand over your opponents forearm and , while maintaining contact, slide it past the crook of your opponents elbow. You will need to move in very close for this to work. While you might do it in a single lunge, it is easier to make a shuffle step to close in from the picture point of the 13th scholar. Although Fiore cites this as being the play of the 1st scholar of the 1st master of dagger, due to the weapons involved, a better indicator of what this look like is the 4th scholar of sword in one hand.
Lock your left hand around your opponents upper arm, just above the elbow. Pull your elbow back to your core to rest against your body. At the same time, wove your hand in an anticlockwise circle until it rests in front of you at shoulder height.
This will lock your opponent up, twisting them off balance and causing them to drop their sword. There will be ample opportunity for you to stab or strike at will.
The initial play can also seen in the following
The continuation onto the bind can be seen in the following