This is the second play from the previous beat. I strike this man over the head, for I can see that the head is unarmoured.
This play is the same as the 2nd scholar of the Sword in one Hand. The only difference here is that it is delivered from horseback rather than on foot.
From the Master play of Posta Coda Longa, cut over your horses head and strike diagonally upwards, beating your opponents weapon up and to your right. Be sure to finish the beat in a properly formed Posta Fenestra. The forward momentum of the horses will put you in range to cut back down along the same line, striking your opponent in the head as shown.