A manifestation of will, for one. You don't need to concern yourself about the details of it.

[That's all he needs to know. A breakdown of Call of Chaos + Hereward powers isn't on his teaching agenda today. Or ever. ]

But what do you mean 'I think'?

[Tone rigid, irate and tense - I think isn't the confident declaration he would expect from someone absorbing what's theirs. He doesn't want to spend all day tracking down another wayward person's original power and it's reckless to leave him with something unknown, in a sea of stolen abilities.]