Warriors raised on the concept of the glory of combat would see the slaughter of the unresisting as repugnant, even if they had no other moral grounds for not killing the Anti-Nephi-Lehies.
Redaction: The connection between verses 23 and 24 is somewhat awkward. Verse 23 is based on description, but verse 24 is an aside, inserted to explain the Lamanites’ state of mind. It seems more likely that Mormon, imaginatively and sympathetically, entered into this mental state than that the author of his source text did. Mormon is even more clearly the source on the Lamanites’ thoughts in the next verse.