Defending What Was Entrusted The flocks, the robbers, and the arms they brought to the king
The incident at the waters of Sebus looks, at first reading, like an action sequence inserted to demonstrate that Ammon was physically impressive. It is more than that. It is the story of a man who took the responsibilities of his position — however humble — with complete seriousness, and whose commitment to those responsibilities opened a door that no amount of preaching would have opened.
A group of robbers scattered the flocks. This had happened before. Previous servants had been killed for it. The other servants began weeping when they saw the flocks scattered, because they knew what typically followed. Ammon's response was immediate: he organized them to gather the flocks, then positioned himself at the water — the narrow point where the robbers would have to pass — and stood alone against them.
"Therefore they did not fear Ammon, for they supposed that one of their men could slay him according to their pleasure, for they knew not that the Lord had promised Mosiah that he would deliver his sons out of their hands; neither did they know anything concerning the Lord; therefore they were not afraid of Ammon."
Alma 17:33 The robbers were not afraid of him. They were wrong. When they attacked, Ammon used his sling against the chief robbers and then used his sword against those who raised weapons directly against him. The text records that he "smote off their arms" — several of them — and the rest fled. The servants gathered the arms and brought them to Lamoni as evidence.
Lamoni's response to hearing what Ammon had done is revealing: he did not respond with military enthusiasm or gratitude for good service. He responded with a question about who this man was — and specifically whether he was "the Great Spirit" (Alma 18:2–3). The king's framework for understanding power was spiritual rather than military. A man who fought like this without being killed was either divine or operating under divine protection. From that question, the door to the actual teaching opened.
Ammon did not plan this. He served faithfully, an extraordinary event happened through that service, and God used the event to create a question in Lamoni's mind that no prepared missionary speech could have produced. The principle is not that you should cut off people's arms to create teaching opportunities. The principle is that faithful, excellent service creates credibility that opens doors that words alone cannot.