Let him have his fun, Noct--and really, it was just to get it closest to the wound. Honest!

Ignis knows enough, mostly from asking questions of Felih, that he can put two and two together--the gods she knows are dangerous, and the ones they know of are allies. (The healing being similar to Felih's magic really only makes that easier to determine.) The question of how she knows Noct's title, however, makes him stay very close to his king--and he rests a hand on Noct's shoulder in a calming gesture.

He's letting the two of them talk for a moment, ready to intervene--and his eyes are squarely on Pinya. With his worry about Noct gone, his emotions slide away. Ignis is ready to act against her if she makes another move towards Noct, even though he's certain the fight is over.