兜の緒を締める
1
to brace oneself (e.g. for battle);to pull oneself together;to focus one's mind;to tighten the strings of one's helmet
oft. as 勝って兜の緒を締めよ
See also:
勝って兜の緒を締めよ (かってかぶとのおをしめよ)
Other forms
かぶとの緒を締める 【かぶとのおをしめる】 (search-only kanji form)