When I think of questions, I will. I didn't have as much exposure to it back in my world, except in the hands of our universe' Kai. Mostly in training to stop an evil-wizard from reviving a threat to said universe.

[Trunks will hold his hand and the ball of ki up closer for Dumbledore to see. It's not simply an aura, it's actual energy. Faintly hot, swirling, and bright.]

Training. Again, it's usually done via Martial Arts, and starts by being aware of one's senses and how one's own body and mind and energy work.

[His tone went slightly softer, mostly because he wasn't trying to brag but more inform.]

My father was an alien-race, and his people have an advantage in learning to manipulate and use Ki, but humans can do it too. Other aliens were even more adept at it.