understanding or capable of understanding the secret or mystery (behind something).

hitting at the vital parts, vulnerable spots, etc.

causing much grief or mental anguish.

a man or something that causes much grief or mental anguish.

he who can understand the secret, mystery of something or vulnerability of another (esp. of a rival or enemy).

a woman or something that causes much grief or mental anguish.

she who can understand the secret, mystery of something or vulnerability of another (esp. of a rival or enemy).