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This play represents an in-tempo counterattack performed agains a halpschilt siege. As the scholar is cutting from above, the priest cuts also from above so that his blade slides between the opponent's blade and his shield. He is at the same time stepping back, so the whole action is similar to falling under. Except for that the cut strikes from the other side of the sword.
The text tells us that this is a technique that common fencers do. In the last image, the scholar counters this action by rotating the shield and sword 90 degrees (so that the blade cannot slide between them) and thrusting.