Translation
If I am crossed in narrow play, I immediately do this hold because neither with sword disarm nor bind can he retaliate. Also I can injure him with thrusts and cuts without any danger to myself.
Interpretation
This is a fun and interesting way to jam your opponents weapon. Although the application is very different, there are similar principles at play here as you see in the 1st scholar of the 3rd master.
The set up for this play requires quite a strong beat at the master play which precedes it. From the crossing of the swords, you want to hit your opponents sword hard enough that it angles off to your left. You are going to exaggerate this movement.
With your left hand, make a hooking block under your opponents right wrist. This is a technique Fiore frequently uses, most notably throughout the plays of the 1st master of dagger. Lead with your left thumb under handle of your opponents sword and onto the inside of their forearm.
Immediately you make contact, roll your wrist over and grab onto the forearm. Step through with your left foot as you do so, and pull the elbow in close, locking it to your core. The turn of the wrist, coupled with the leverage of your forearm will force your opponents blade right over, as the picture shows.
While all the action is focused on the left hand, bring your right hand back to lock against your ribs. Your right hip is chambered for an attack. The sword blade effectively extends directly from your core. Use your wrist to target the point. As your left hand pulls back, your right hip pushes forward, driving the blade through your opponent.
A slight variation of this play can be seen in the following