The four people who were able to make it to the 3rd step were all Middle-Stage 1st Circle Aura Knights. There was some correlation between the aura level of the candidates and how far they were able to get, but it wasn't the only reason they were doing better.
Some Middle-Stage 1st Circle Aura Knights were still stuck on the second level and couldn't move up. There was a difference between those two people. Another thing to consider was that the test was to see how good their body was to train aura.
So it made sense that people who got further were better than others when looking at their aura level. The main thing that Leo noticed was that everyone was using their aura from the second level onward, so he figured that it was also a reason why 1st Circle Aura Knights had an advantage.
