This is the 9260th most frequent Japanese word.
留め
"留め" (とめ) means "fastener" or "closure."
留め (とどめ) in this context means to keep or retain something, such as information or a record.
彼はその事件について記録に留めておきました。
He kept a record of that incident.
留める (とどめる) refers to keeping or containing emotions within oneself.
彼女は感情を胸に留めることができませんでした。
She couldn't keep her emotions inside.
留め (とどめ) here signifies a decisive action or finishing move in an event.