Maybe jav stabs shouldn't rear them that's a reasonably idea maybe; to hijack your thread, I also don't see why slashes from polearms into their face don't rear them. Also, if there was a damage threshhold that could make it really hard to rear a horse moving slowly, not necessarily opposed to it in principle but it seems like things which hit them hard in the face in general should make them rear if we're going to have that mechanic.