To take from its scabbard, as a dagger.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (verb) (v. t.) (verb transitive)
To draw from the sheath or scabbard.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (verb) (v.) (verb)

Usage examples:

Unsheathe thee then, thou treasure, Of soldier's eyes the pleasure; Come forth, my Sword, come forth, On!
- The Student-Life of Germany by William Howitt
There were no more fights with knives, although when my wound was healed he did broach the subject again on two or three occasions, and was anxious to convince me that it would be greatly to our advantage to know how to defend ourselves with a knife while living among people who were always as ready on any slight provocation to draw a knife on you as a cat was to unsheathe its claws.
- Far Away and Long Ago by W. H. Hudson
In the suggestion that such poor quarry as waits us should be worthy thine endeavour, should warrant the Lion of the Faith to unsheathe his mighty claws.
- The Sea-Hawk by Raphael Sabatini