Sans will judge you for your actions, if you fight him, you will be faced with consequences as he will fight you with blasters and bones. However, you can choose to try and resolve things with sans. He will doubt your actions as first, but if you will tell him to reset, he'll accept it for now. He will spare you if you do so. Sans has bone manipulation, blasters, telekinesis and teleportation. He can't get hit at all or he'll die. However, he has a lot of stamina and can dodge.