@Arcverson: Initially he was wary when the fox claimed itself to be a "God", since back in the fantasy world he couldn't compare to the Goddess who summoned him.
But then it turns out this self-proclaimed God is about as far from the Goddess as Kuro to D.
Now I think he just want to absolutely crush its will as revenge for hurting his friends.
i.e. "Go on, power up to your final form, THEN I WILL CRUSH IT TO SO HARD YOU WILL QUESTION YOUR OWN EXISTENCE"
His surprise was more of "oh wow, this is weak ass crap, why is it so proud of it"