Well, when it comes to these kinds of discussions splitting hairs is where most of the debate occurs. For instance, I agree that ready effects are fine in Spirit, but I draw a distinction between a character readying himself (or herself with Idrean) and an outside effect readying a character. When the ready effect is internal it exemplifies spirit. When an outside force ready that signifies leadership. Now by this UC is perfectly within flavor, so I my problem with it is more that it is too cheap (should probably cost 3) or should be limited to blue heroes. Those kind of limits don't apply to purple IMO. That being said, I also love the flavor of food having a ready effect (cram, lembas). All such comments from me are in the tone of "if I designed LOTR" and not meant as an criticism of the actual game :-)

I think that Spirit is mostly good for questing boost and threat reduction.

Leadership is mostly good for readying effects and for resources.

In addition to readying and resource acceleration, Leadership has stat-boosting as a sub-theme. Dúnedain Warning, Mark and Quest, For Gondor!, Sam Gamgee, Durin's Song and Celeborn all being examples.