Like Ren, I have my guesses, but for now Itsuki cannot lie, so it would be faster just to ask him.
The current Itsuki just says whatever pops into his head.
If we ask him about these powers, he’ll probably answer.
“Itsuki, what powers would you be talking about? Do you mean about the power of the legendary weapons?” (Naofumi)
“No. The legendary weapons may have a similar function as well, but I’m referring to something completely different. Isn’t it obvious?” (Itsuki)
“Hah… Please elaborate. In the world that you came from… what were these powers?” (Naofumi)