「......てめえ、覚えてろよ」
「女の子はそんな言葉遣いしちゃ駄目よ。そうそう、仕上げにこれをつけてちょうだい」
「あ?」
士道は眉をひそめながら、琴里から絆創膏のようなものを受け取った。
「それをのどに貼り付けてみて」
Context: the first speaker is the brother (士道) and the second speaker the sister (琴里). The sister forced her brother to dress as a girl. And she gave him a device for him to stick to his throat, so that the brother’s voice could change into a girl’s voice.
Hi. What is the function of the に in 仕上げに? Is the に the same as として? Or does the に indicate purpose? Thank you.