At first the beautiful assassin must have thought that Eric wasn't much, as he wouldn't be using this roundabout way if he was truly something.
Not only did this way take a lot of time, but he didn't enjoy it much. After all, the ladies were doing the job for him, and he was only watching.
In fact, Eric could have done that from the start and personally show the beautiful assassin who was the Master, but he didn't do it just for false pretenses.
He wanted to make the beautiful assassin lower her guard as much as possible before giving her a hit that she would never be able to recover from, and he definitely did so.
Whether the beautiful assassin licked it or not, the moment that she exploded like a volcano and lost her conscience for that brief moment, she had already lost the war.