Silver Horn/Elven Crown Morale

[Vulture]

Hi everybody!

What are the requirements for the Morale of these items to rise ? I cleared most of lotd, didn't kill a single elf related unit and I had Hunters in my army on which I eventually casted a heal or ress. Still the morale dropped by 3 every battle. It's annoying going to a garrison to "park" the units exceeding my leadership without the crown, supress it, pack the units and travel back to where I'm fighting/questing.

Does it only rise with more elf units ? Does it only rise during battles against dwarves ? I thought at least it will remain killing no elves.