The most USELESS monster.

No, not at all... in principle, only if you have an army from the Castle of Death, then the Fairy will have low morale (and the Inferno branch, it seems, too).

No way! THIS WON'T WORK! Where is it written that we are discussing the benefit, from the point of view of Death, and morale?
There's no need to reduce everything to a specific case.
I can just as easily say that people will have low morale if they have a Bone Dragon instead of a Squire.
That argument doesn't hold water!