Shaolin Kung Fu
Specific special skills accumulated through his vast experience include picking locks, some proficiency in Shaolin Kung Fu, handgun training, multiple languages including Russian and Hawaiian, and playing-card throwing. One of his dupes was a S.H.I.E.L.D. agent, giving him all the prerequisite espionage training. Along the way, he or his duplicates participated in an Olympic gymnastics team and apparently became a licensed attorney.