Assassins morale and other buffs

[Liger]

Morale:
Fool's Cap (don't work)
A jester's hat, decorated with silver bells.
+3 Intellect
+1 Morale to all troops
Army Drum (don't work)
Normal signal drum.
+150 Leadership
+1 Morale to all troops

Other boost:
Assassin's Dagger
Narrow long dagger with a poisoned blade.
+1 poison damage
+30% to Critical Hit of Assassins

I haven't tested those "morale to all troops" items on neutrals, but I think those should work.

[the benevolent adversary]

actually I believe neither of those morale artifacts will work on anything but human, and though it seems the assassins are human I do not think it will work on them. but hey try it out I could be wrong.
personally I would rather use the royal snakes then the assassins, they can be buffed if you want (I also usually get the blue pet dragon which gives them a higher initiative).
if you are getting lots of criticals then the jolly roger sword is sweet (adds 20% damage to critical hits).

[Liger]

The benevolent adversary is rigth. I just tested both morale items and it seems that those give morale only to humans. Stupid missleading info though.

Of course one way to give them morale is make your own item with editor then add it to some shop or chest.