Water Fairy had to face this Thief Puppet alone. Lu Li couldn't help her on this one, or else Garona wouldn't see as highly of her.
Although Garona was nice to Water Fairy, Water Fairy wasn't her real student. Since they requested a trial, it meant that the trial results would be very important.
You could never be too good in front of an NPC.
Lu Li dealt with three other monsters by himself so that Water Fairy could focus on the one before her. Lu Li didn't actually need to worry about her at all.
No matter what, she was still a celebrity player and had faced challenges of her own. There was no way that she would become weak just because someone was watching over her. Just by her technique alone, she could make it into the top ten Thieves in the game. With her equipment and skills, she could easily be the top five. Only a few players like Lu Li, Wood Fearing, Blood Dagger and a few others could put up a fight against her.