The Collaborative International Dictionary of English v.0.48:

Nib \Nib\ (n[i^]b), n. [A variabt of neb.]
   1. A small and pointed thing or part; a point; a prong. "The
      little nib or fructifying principle." --Sir T. Browne.
      [1913 Webster]

   2. (Zool.) The bill or beak of a bird; the neb.
      [1913 Webster]

   3. The points of a pen; also, the pointed part of a pen; a
      short pen adapted for insertion in a holder.
      [1913 Webster]

   4. One of the handles which project from a scythe snath;
      also, [Prov. Eng.], the shaft of a wagon.
      [1913 Webster]

   5. pl. See his nibs, below.
      [PJC]

   his nibs Someone who gives a command or makes a demand,
      often one who acts in a self-important manner, sometimes
      one with authority; -- used mockingly as a jocose term, as
      if a title of honor, but not usually in the presence of
      the person referred to, and usually indicating resentment
      or contempt. [Colloq.]
      [PJC]