What does John 18:10 mean?

When Jesus made reference to how He would be facing these events alone (John 13:36), Peter responded with a brave claim (John 13:37). Since the disciples are armed (Luke 22:38), Peter apparently thinks this is the moment to prove his sincerity. As Paul will point out later (Romans 10:2), passion is not the same as perspective. Literally everything about Peter's approach here is wrong: his method, his goals, his target, and even the results are the opposite of Christ's intent.

It's important to remember that Peter is a fisherman, not a soldier. The weapon he's holding is described as a machairan in Greek, a term referring to a short sword. This is the same term used in Hebrews 4:12 referring to Scripture's ability to "separate" things. Most likely, this is an oversized fisherman's blade.

The effect of Peter's swing brings up interesting possibilities. In that era, being right-handed was more than a preference, it was practically mandatory. For Peter to swing a blade right-handed and hit another man on the right ear is awkward. Perhaps he swung overhand, nearly missing on the way down. He might have tried to draw and slash outward in a single motion. Less likely is that the man as facing away from Peter, possibly having turned to run. However, Peter would have had no reason to target a servant. A more intriguing possibility is that Peter was clumsily swinging at someone else, and missed. Given that Judas is standing close by (Luke 22:47–48), it's not unreasonable to wonder if Peter was trying to kill the traitor (John 18:2–3). Scripture gives no such explanation, however, so all we can do is wonder.

Here, again, it's clear John is leaving known details to the other Gospels. This verse, and the next, are matter-of-fact and brief. John's intent here seems only to add the name of the servant who was struck, making no mention of Malchus being healed by Christ (Luke 22:50–51). John's inside knowledge of the high priest (John 18:15) meant he may have known Malchus, personally.