The Collaborative International Dictionary of English v.0.48:

Virtuosity \Vir`tu*os"i*ty\, n.
   1. The quality or state of being a virtuoso; in a bad sense,
      the character of one in whom mere artistic feeling or
      aesthetic cultivation takes the place of religious
      character; sentimentalism.
      [1913 Webster]

            This famous passage . . . over which the virtuosity
            of modern times, rejoicing in evil, has hung so
            fondly.                               --C. Kingsley.
      [1913 Webster]

   2. Virtuosos, collectively. --Carlyle.
      [1913 Webster]

   3. An art or study affected by virtuosos.
      [1913 Webster]

WordNet (r) 3.0 (2006):

virtuosity
    n 1: technical skill or fluency or style exhibited by a virtuoso