Incisive

a.
  1. Having the quality of incising, cutting, or penetrating, as with a sharp instrument; cutting;
  2. (Anat.) Of or pertaining to the incisors; incisor; as, the incisive bones, the premaxillaries.
  3. Clearly and succinctly stated, with penetrating insight into the issue at hand; as, an incisive comment.