The Fourth Master position defends against a downward vertical attack with two hands grabbing the weapon arm.
The Fifth Master position includes an attachment (shoulder grab) by the opponent. The first plays deal with the attachment directly, as a preemptive strike, or because the dagger itself is somewhat delayed. Then we ignore the attachment in the cases where the dagger is coming more immediately, and make our sure defense against it before counter attacking.
The Sixth Master defends against a rising blow to the belly or chest. We'll make our defense with both hands (similar to the fourth master), and then work our counter attacking plays to conclusion.