This is the first play from Posta Coda Longa shown previously. The Master beats aside the sword of his enemy, and puts the sword in his chest or face, as drawn here.
As the 1st scholar, you beat your opponents sword as you move from Posta Coda Longa to Posta Fenestra, very simliar to the Master of Sword in One Hand. This clears a space for you to put the point of your sword into the front of your opponent. For the most part, you will need to focus on controlling your sword point to the target. It is the forward movment of the horse which delivers most of the power that does the actual damage.