When Samuel originally attempted to preach to the Nephites he was rejected, and was returning home when the Lord required him to return (Helaman 13:2-3). Those who rejected his message before were in no different frame of mind now, and indeed had become murderous. Just as the Gadiantons had attempted to kill Nephi to remove him as an influence among the people, so these Nephites are now attempting to kill Samuel. This would also remove Samuel from the minds of the people. The attempt backfires, however, as noted in the next verse.
Cultural: The fact that arrows were shot at Samuel suggests a planned murder. Arrows were either hunting weapons or weapons of war. They were not the kind of thing that one would be carrying around on one’s person on the way to market. To have shot arrows at Samuel, either there was a standing army (and the evidence is against this possibility) or there were many who began to listen to Samuel, and consciously went to some location where they could retrieve their arrows and bring them to the spot where Samuel stood. This need to leave and come back also indicates the reason that Samuel had time to give the sermon. Had the people already had their arrows with them, they might not have allowed him to speak at all, or certainly not get nearly as much information out before they attempted to kill him.