Sharpen; improve (skills) (4)
I believe the answer is:
hone
(Other definitions for hone that I've seen before include "Polish" , "Sharpen tool on stone" , "Smooth stone" , "Strop" , "Sharpen (a blade)" .)
I believe the answer is:
hone
(Other definitions for hone that I've seen before include "Polish" , "Sharpen tool on stone" , "Smooth stone" , "Strop" , "Sharpen (a blade)" .)