Valour also increases the morale of a unit - usually by 2 points of morale for every 1 point of valour.

For a full understanding of why some units gained valour at the end of a battle, while others didn't, take a look at the battle logs afterwards.

(If you havn't done so already, you'll need to enable the battle logfiles by ticking the box in the game options menu).

The unit's valour is actually an average of all its members individual valour scores. Retraining a valoured cadre will top it up with fresh 0-valour troops and thus lower its average, although the previous members retain their valour record, as will be seen if they go into battle again.

Because of this averaging business it turns out that, a lot of the time, the valour gained in battle is mostly a side-effect of suffering a high percentage of casualties.

It is probably better to merge valoured veteran cadres together, to maintain their high average, than to retrain them. The benefits of the improved valour are at least as good, or better, than those of the improved equipment.