I thought it was because of his impure feelings like greed because he's in love? I'm not sure though.
Same, and yes, definitely after the temple. Seems like he unlocked something then when he was worried about Ivona.
Maybe... I was thinking more along the lines of the left-over power in the temple tainting his own power
I remember his mother saying something about demons tainting him/consuming him
I don't remember that at all , maybe I should re-read it
I love Claude but the dark swirls that go around him when he gets angry give me bad vibes :(. I actually came back to this after a long break, did those swirls start appearing after they visited the abandoned temple? I seem to remember something like that, if so, did the Holy Sword also stop listening properly after he visited the temple as well? ;;