I believe God was telling Gideon that if he just trust, believe and have faith, that He would be with him and together, they would conquer.
The principle does apply to all Christians. God said that the battle was not ours and that vengeance was His.
I feel that asking what is the appropriate prayer, has a universal answer. Simply praying, "Father, help me to fight my battles. In the name of Jesus", will get results. Just the same as:
Father,
In the name of Jesus,
I pray for guidance with this situation. You said that You would be my Comforter, my Helper and my Strength. I know it is Your will that peace should be a part of my day, so I am giving this situation to you and I am believing right now that You have already began to give me victory. I am thanking you, in the name of Jesus, for I know it is already done. This battle is yours.
In the name of Jesus
Amen