The third floor represented the pinnacle of commercially available medicine. Epic-rank treatments that could reshape human physiology.
Exactly what Charlotte needs. Although it would have been good if Legendary rank items were available. Unfortunately, they aren't.
Legendary rank herbs, Items or weapons were all treasures that every elite family kept for themselves. After all, Legendary items weren't things that were easy to come by. And each item significantly enhanced the user's power, or, in the case of herbs, could potentially save them from a fatal, non-conventional wound.
Access to the third floor required a large amount of reputation points accumulated through guild activities, academy achievements, or political connections. As Power Guild's leader, Academy of Mera student, and guild council member, Arthur possessed credentials that opened every door.