Everyone was thinking that Julius was the one behind all the misfortunes that came to Nero but the truth was Julius did not do a single one of those things. The ones who did all of that were those who wanted Julius to become patriarch.
On the other hand, Julius never thought of using any underhanded tactics during these five days since he truly believed in his victory in the duel. Everything was going as he envisioned with Ren saying that anything goes, with that in mind Julius could use everything at his disposal.
Unlike, Nero who was born with all the best qualities a member of the Loder Clan could have, he was born as a weakling. Granted Julius was stronger than normal people but that's compared to normal people outside of the clan within the clan he was not even at the average strength threshold.