Right now, if he really tried his utmost, he would probably be at the level of Level 6 Advanced [Senior Elder] and would only be able to defeat a Level 6 Intermediate [Elder] with all of his efforts.
As for a Ranker with the power of a Level 6 Beginner [Junior Elder], after the fight outside the Ant Hole, Yue Yang realized that he could actually defeat them easily.
Level 5 and below were all ants to him, he could kill them all very easily.
As for the defeating the Marquis of Zi Jin, other than due to his own capabilities, it was also because that fellow had underestimated him and had battled with Grandma Chi before, losing a lot of his battle power. That was why he had gotten away so easily. If the Marquis of Zi Jin had known his true strength and attacked him with all of his strength from the beginning, Yue Yang would have a headache. Had Marquis of Zi Jin fought him in his peak condition, he would probably have emerged as the victor in the end.
Yue Yang felt that would he would only be able to fight against the Marquis of Zi Jin if he could understand his [Yin] power and master the ability to control water and ice, then master Level 4 of Innate Invisible Sword Qi.