Reckless

Teancum seems to have been reckless when he went after Ammoron at the end of the war. When he had killed Teancum he was desperate to end the Lamanite advance while he had minimal support. In contrast, when he killed Ammoron the neighbors were firmly in control of their position and the momentum was in their side.

I’m not trying to dunk on Teancum but we do have to learn what was different between his two actions (besides him being slightly less precise with his javelin).