The Collaborative International Dictionary of English v.0.48:

Deftness \Deft"ness\, n.
   The quality of being deft.                     --Drayton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

deftness
    n 1: skillful performance or ability without difficulty; "his
         quick adeptness was a product of good design"; "he was
         famous for his facility as an archer" [syn: adeptness,
         adroitness, deftness, facility, quickness]

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "deftness":
   ability, address, adeptness, adroitness, agility, airmanship,
   artfulness, artisanship, artistry, assuredness, bravura,
   brilliance, capability, capacity, cleverness, command, competence,
   confidence, control, coordination, craft, craftsmanship, cunning,
   dexterity, dexterousness, dextrousness, diplomacy, efficiency,
   expertise, facility, finesse, fleetness, grace, grip, handiness,
   horsemanship, ingeniousness, ingenuity, know-how, marksmanship,
   mastership, mastery, nimbleness, practical ability, proficiency,
   prowess, quickness, readiness, resource, resourcefulness,
   savoir-faire, savvy, seamanship, skill, skillfulness, sleight,
   style, tact, tactfulness, technical brilliance, technical mastery,
   technical skill, technique, timing, virtuosity, wit, wizardry,
   workmanship