The folks in the martial arts school my brother trains in actively try to cultivate a really intimidating "crazy stare" just to try to unnerve each other in sparring matches - and because it looks darn funny if you're not on the receiving end. No, they're not all that reverent about many things. On the more practical side that also gives them practice in dealing with such psychological attacks...

Anyway, in mass warfare intimidation had a rather important role - besides sheer vanity, that's the primary consideration behind all kinds of tall crests, highly polished and decorated armours, war cries, beating shields, and so on and so on. After all, you won battles by making the other buggers run away and then cut them down at your leisure. Particularly important in cavalry-infantry match-ups, where psychological factors make the critical difference between a charge pulling short and the footsloggers being ridden down down with near impunity.