What does Matthew 26:51 mean?

A crowd of soldiers and temple police have been sent by the chief priests and elders to arrest Jesus (Matthew 26:48–50). One of His own disciples, Judas, has led them here and has identified Jesus with a kiss (Matthew 26:14–16). Jesus is not resisting or attempting to run.

One of the disciples, though, resists with violence. John tells us that disciple is Peter (John 18:10), which is not a surprise. It's possible Peter was still stinging from Jesus' declaration that he would deny the Lord three times before morning (Matthew 26:30–35). Peter had insisted that he would not abandon Jesus and would certainly die with Him. He was clearly ready to take his stand with Jesus against an entire crowd of armed men.

Of course, Peter is no soldier. In that era, it was assumed that all people wielded a sword in their right hand. For Peter to hit his target's right side (Luke 22:50) suggests a strange incident. Either Peter swung overhand, or missed at first and took another swipe, or the target was facing away from him at that moment. Some commentors suggest that Peter was taking a wild swing at Judas and simply missed, striking a man nearby. For whatever reason, and in whatever way, Peter succeeds in cutting off Malchus' right ear (John 18:10).

Jesus makes it clear in the following verse that Peter was missing the point. He was using the wrong method, at the wrong time, on the wrong person (Matthew 26:52).