A person's dominant hand — the hand mainly used for tasks like writing or handling tools (right- or left-handed).
彼は生まれつき利き手が左だ。
He is left-handed by birth.
利き手を怪我したので、しばらく不便だ。
I injured my dominant hand, so it's inconvenient for a while.
ピアノの練習は左右の利き手を均等に鍛えることが大切だ。
Piano practice should develop both hands equally, not just the dominant hand.
A skilled or capable person; someone considered a master or chief performer in a particular skill or field.
新人チームにベテランの利き手が加わった。
A veteran ace joined the rookie team.
あの店の利き手は寿司を握る職人だ。
The shop's star is the sushi-chef — he's the skilled craftsman.