Source : Webster's Revised Unabridged Dictionary (1913)

Unsheathe \Un*sheathe"\, v. t. [1st pref. un- + sheath.]
   To deprive of a sheath; to draw from the sheath or scabbard,
   as a sword.

   {To unsheathe the sword}, to make war.

Source : WordNet®

unsheathe
     v : draw from a sheathe or scabbard; "the knight unsheathed his
         sword" [ant: {sheathe}]