The morale thing is indeed much more realistic. Many a war have shown how veteran units hold where others would break and run. And how a small core of veterans surviving battle after battle continue to do so while Noobs die, and continue to put backbone into their unit. Of course, such vets are more lethal as well, but it is their morale that plays a significant role.

Imagine standing next to a veteran legionaire, facing eles, naked berserkers or some other scary occurance (even more scary than the mere concept of a battle and consequences of such to your tender flesh) and he just stays calm and tells you it is no big deal- having seen it all before. From talks to veterans of our modern-ish wars I can tell you such means a lot. that, training and the friendship with the other guys in the subunit, a Contubernia fx.