Dryx
After he defeated Jase, Nial was rarely challenged. The few challenges he had received were from promising young Originals, who had wanted to test Nial's strength, or ignorant Originals, who hadn't heard the rumors about Nial.
In the end, all of them left him alone and decided to not irk him. As such, Nial didn't really have any problems continuing with his tight-knit schedule thanks to the great performance he delivered during the first time he had been challenged.
That was why the remaining two months of the hellish training passed without much disturbance.
However, that was only the case for him. While Bella was also not challenged that often after delivering a similarly overwhelming performance the first few times somebody thought of dueling with her, Mathias had struggled a little bit more.