Lady Stefanie had smelly socks and she wanted to use them to torture this guy. She felt that it was the best thing to use to punish him as his mistake did not rise to a level that required pain. So the mistress used her stinky socks to dominate the guy and to get him to see things from her perspective. He appreciated her perspective after going through the humiliation.
Lady Stefanie did not like how forgetful her slave was and she wanted to show him it was not ok with her. The mistress used her socks to pass the message. He had to learn that she was not the kind of person to tolerate such a thing. So the mistress made him lick her socks and she promised to trample him and to choke him if he did not change.