Rejuvenate
After the last berserker died there was a moment of elation, followed by extreme exhaustion. Nero was better off, not only because he had long been training his body to have exceptional endurance, but because of his recent strengthening.
Even then, his condition was not exactly the best, let alone everyone else. It was easy to say that they had rested for a few hours earlier, but in truth their body had not recovered from the constant exertion of fighting so many curses.
Nero had thought that having low aether would be his greatest concern, but he underestimated the physical exertion he had to face. This may be one of the most important reasons most soldiers are encouraged to reach the Initiate realm as quickly as possible. The boost the human body received was much needed for such drawn out missions.