Yes it is true, Manasseth had undergone that meditation training with Amaimon and he clearly saw the Genki next to Alexander. The Genki's response to Alexander's description of him amused Manasseth, but he held in his laughter as he remembered how Amaimon's Genki, similarly to Alexander's, easily got angered. And we don't be wantin' to anger da spirits, mon! With a joyous smile that would close his eyes, Manasseth waves "hello" to Gaidar then averted his attention from Gaidar to Alexander as the teacher spoke once more. And now, time to review.
So from what I've learned so far, I understand that the "root" of our abilities revolves around us being capable of communicating with spirits from the Pure world and have them aid us in the Impure world, our world, by befriending then. Genkis, in themselves, are made of some sort of energy that belongs to the spirit world and their personality seem to be somewhat... childish and not very civilized. (Gaidar, plz don't kill meh) Being able to communicate with spirits, in itself, allows us to perceive all kinds of spirits, which I've been told the clan calls aura sensing. As for how the Genki's aid us in battle, we can have them infuse themselves into certain objects, which would then give said object living properties, so to speak. As in, make a certain object reshape itself into the form of a certain being and move by its own will. Genki's can also partially possess us or fully fuse with us to enhance our own being or have our entire being and the Genki's completely fuse with one another. Basically making us become "one".
He paused for a bit...
I think that is all.