of vital use to 意味

• ～に極めて利用価値｛りよう かち｝の高い
  

例文

1. although ryoma lost support from katsu , ryoma asked kichinosuke saigo (takamori saigo ) for help on referral from katsu , and ryoma was harbored at satsuma clan ' s house in osaka , on which some point out that satsuma clan helped ryoma because they thought that ryoma would be of vital use to navigation skills ( " verification: the legend of ryoma " by rei matsuura ).
   勝の庇護を失った龍馬であるが、勝の紹介で西郷吉之助（西郷隆盛）を頼って大阪の薩摩藩邸に保護されるこれには、薩摩藩側が龍馬らの航海技術に利用価値を感じた点も大きいと指摘されている（松浦玲『検証・龍馬伝説』など）。