piece under one's control; pawn; subordinate
Refers to game pieces, soldiers, or people that one can move or use as one wishes. Often used figuratively for subordinates or resources at one's disposal.
In shogi, captured pieces can be used as one's own pieces.
He moves his capable subordinates around like pawns.
Compound of 手 (hand, one's own) and 駒 (piece, especially in shogi). The figurative extension to people under one's control is natural from the shogi usage.