>An expert or skilled person
>One skilful at
>Someone incredibly skilled at a task
The noun phrase a dab hand is usually followed by “at.”
Dab hand apparently originated as Yorkshire dialect pre-1800 but didn’t become widely used in Britain until the 1950s.
Example
>She is dab hand at south indian cooking
>I am a dab hand in touch typing on a computer keyboard more than on a mobile phone.