I was informed this is a scene in the martyrdom of Saint Gregory the illuminator, one of the scenes where he is being tortured. He is hung upside down with two ropes that are attached on his feet. A salt bag wraps his body to make it heavier and more painful for him.

There is another fresco, also of the saint hung upside down, but that oen is at the entrance. This one can be seen on picture nr. 5626.