Prajna, or discriminating awareness, is aware of itself in such a way that it is a sword that cuts its own blade. It’s so fast and precise that it cuts itself. This doesn’t blunt its blade. That blade sharpens itself by cutting itself. Then there is another level, which is the awareness of skillful means, which is being aware of how and when to use the sword. The use of the sword creates feedback to the swordsman.
From Illusion’s Game: The Life and Teaching of Naropa by Chögyam Trungpa, page 79