Everyone has a weak spot. The key is to find it and put something pointy there, preferably from a safe distance.
This is the archery school of precision. If there is a single scale missing on a dragon's stomach, a Falcon's Eye adept will find it. Many practitioners of Falcon's Eye also study Shadow Hand, to better strike from hiding without fear of retribution. Others prefer to stand behind ramparts. They do not call this cowardice, merely sense: they are not there to be wounded, but to deal wounds (and death).