Expert ( Informal ) (3)
(Other definitions for buff that I've seen before include "In good shape, muscular" , "with attractively well-developed muscles" , "Informal enthusiast - polish him" , "Polish; yellow-beige" , "Adept; yellowish-brown" .)
(Other definitions for ace that I've seen before include "Crack" , "Test pilot'" , "Girl" , "One-spotted card" , "Playing card with single spot" .)