noun
signature move; finishing move
Primarily used in martial arts and professional wrestling to refer to a fighter's trademark technique or finishing move. Can be extended metaphorically to other competitive contexts.
彼の得意技は飛びつき腕ひしぎ逆十字固めだ。
His signature move is the flying armbar.
あのレスラーの得意技は相手を一瞬
That wrestler's finishing move takes down opponents in an instant.
Compound of 得意 (とくい, 'one's forte') and 技 (わざ, 'technique').