Question is concerning this particular item from the Annual 2002:War Horn:
The blaring sound of a war horn can be enough to stir the hearts of any warband which it is attempting to bolster. It grants men courage and gives them the will to fight on defiantly. A war horn may be sounded once per battle at the beginning of any of the player's turn. It allows the warband to increase its Leadership by +1. The effect will last until the start of the next turn. The war horn can be used just before a warband is about to take a Rout test.
As far as I can see, there's no problem in having several Heroes with this and increase the Ld by 1 in 6 rounds. Of course it's expensive, but for my Lizardmen with Cold Blooded, I might consider this. I'll probably not use it with 6 Heroes, but it would be nice to know, if it could be used with more than one Hero pr. battle. Could also see it as useful for Orcs and their stupid Troll