The "reverser"/"inverter" is a technique found in early glosses such as Ringeck & Von Danzig.
The fencer, having achieved a bind with the opponent, redoubles their attack by thumbing the blade and attacking by inverting the blade so you move to thumbing it more from below with somewhat of a winding action to thrust from above.
As the opponent displaces the blade to their left, step around and grasp them by the elbow with the left hand, and shove it aside.
The texts suggest you can use this as a throw by springing with your left foot in front of their right. Alternatively you can use the reverser to run through and thrown (see Einlauffen).
While the movement is seen in the 16th century sources, it is not referred to as the Verkerer.
This movement should not be confused with Verkehren, which is a movement which in some ways uses a similar mechanic, but is entirely distinct.