This is a hold which has neither a counter nor a defence. And here I can take your dagger and binding you is no problem for me. Dislocating your arm will not give me any touble. You cannot leave without my permission. And I can ruin you at will.
The theme of the 3rd master is to cover and step to the outside. Against a fendente stab, make a hooking block with your right hand. Step through with your left foot. Make sure it gets right up close to your opponents front foot. Pivoting on your left foot, arc your right foot around behind you. Use your hips to push under your opponents hips, and so steal their centre. This all needs to be a very fast, light movement. The footwork is identical to the 2nd scholar of the 3rd master of dagger.
As you arc your foot behind you, roll your right hand over and scoop down. With your left arm, keep it close to your body and grab underneath your opponents elbow and lift up. You want to bend the elbow, not hyperextend it.
Be sure to keep pushing against your opponent with your hips. You need to be standing in their space. Continue the movement of your hands in a circle which has your opponents forearm marking the diameter. Drop your left hand tight to your centre of gravity and with your right hand, lift your opponents forearm to vertical. Maintaining contact with your palm, slide your right hand around on your opponents wrist from a thumb down to a thumb up grip. This is a sticky hand technique. Do not let go while doing it. You should finish in the position drawn.
You can now easily manipulate the lock. Keep the forearm vertical and pinned to your chest with the elbow at your centre of balance. The further you lean forward, the more pressure you will apply to the elbow joint. By adjusting the pressure you apply, you can either hold your opponent in place, apply pain, or tear the elbow joint apart.