[thejeff]

When attacking, that would only matter against other size 6 creatures. Otherwise they're trampling and not using the spears. Does repel work against trampling?

When they're being attacked though, those long spears might repels others. There the elephant's low morale wouldn't matter.

Late Arco's elephants do seem to do particularly well against other elephants. And they seem to stand up better when surrounded by troops. Whether that's the better armor or repel I don't know.