With Thor dead and the Citadel destroyed, Arnold was sure this 'Elven Goddess' was too scared to appear in front of him. Either way, he was not complaining as he had achieved more than he wanted to. With Mjolnir in his hands, it was more than enough for him to not destroy the entire planer anymore.
The minute Arnold lifted the hammer and made it his own, the gods along with his summons and the elves were stunned too stunned to do anything. In fact, even if they weren't too shocked, there wasn't much they could have done either way... right?
Some of them did not think about it like that. For them, Arnold was in a weakened state after his battle with Thor. Moreover, his armour was in a fragile state as well, which meant... it was the perfect opportunity for them to defeat him.