Well, that's kind of unfounded. Ovair has no established upper limit, really, you can't just claim that he's of this class and that X is definitively above him. After all, Vitiate entrusted him with eliminating Sith spirits that he considered to be threats to his power.
I agree Sadow was weakened, though, and by a considerable amount, but still enough to make him very powerful. I mean, "Gynt's borrowed powers were formidable", per the Timeline videos. Which isn't much in of itself, but I'm inclined to believe that Sadow!Gynt is still at least Qui-Gon+ tier.
Huh? Ovair's directly stated to be a Jedi Master, lol, not to mention coming from the same heritage as Eison Gynt, namely being widely considered to be the greatest of his generation, which opens the possibility of them both exhibiting that Kun/Revan/Anakin-like potential and allowing them to surpass Master-tier even as mere Knights.
And it's clear that Vitiate entrusted the Ovair family to both infiltrate the Jedi Order and land "preemptive strikes" by eliminating Sith spirits that Vitiate felt might threaten his return to power. Seriously, did you even watch the video? Gnost-Dural directly states as much in it. Timeline 7: Peace of the Republic. Watch it.
Here are the quotes in question.
EISON GYNT WAS A FOURTH GENERATION JEDI, WIDELY CONSIDERED TO BE THE MOST PROMISING PADAWAN IN THE ORDER. HAVING A SIMILAR HERITAGE, THE VENERATED JEDI SCHOLAR, MASTER BAREL OVAIR, TOOK GYNT AS HIS APPRENTICE.
And:
THEY WERE A FAMILY OF SITH INFILTRATORS. OVAIR’S MISSION ON YAVIN-FOUR WAS NOT FOR THE JEDI—IT WAS ON BEHALF OF HIS TRUE MASTER, THE DARK EMPEROR OF THE SITH.THE EMPEROR KNEW THE SPIRITS OF THE ANCIENT SITH LORDS COULD BE A THREAT TO HIS POWER WHEN HE RETURNED TO THE KNOWN GALAXY A CENTURY LATER…
OVAIR’S TRIP TO YAVIN-FOUR WAS A PRE-EMPTIVE STRIKE…
TO SEAL NAGA SADOW’S TOMB AND ENSURE THE EMPEROR’S ONLY ENEMIES WHEN HE RETURNED WOULD BE THE JEDI AND THE REPUBLIC. HOW UNFORTUNATE THAT WE’VE ONLY LEARNED THE TERRIBLE TRUTH ABOUT MASTER OVAIR MORE THAN A CENTURY TOO LATE.