Spiritual war isn’t waged with worldly weapons. We aren’t to attack and kill each other. Instead, spiritual war is a war of hearts and minds. We are to call on our enemies to come out of the world and turn to Christ regardless of the bodily harm they may inflict on us. Our role isn’t to do the fighting, our role is to go wake other people up.

God also states in scripture that we aren’t supposed to be waging physical war. He is the one who is supposed to fight our battles for us. He is the one that ultimately comes and destroys the evil. In your first verse, Jesus is telling His disciples not to fight as that isn’t their job, it is His. You ruin the message of selfless love when you try to convert people with violence, instead, you need to follow the example of Christ.

Michael fought in the war in Heaven because God bears that responsibility and has the power to guarantee an outcome just as He says it will be Him who destroys the ungodly at the second coming.