"As the Sith Emperor’s personal executioner, the grimly fatalistic Lord Scourge has personally killed more than a hundred Jedi–and ten times as many Sith. Even the most powerful members of the Dark Council avoid offending the man bearing the title 'the Emperor’s Wrath.'" - SW:TOR Codex Entry "Lord Scourge".Emphasis mine.
The sheer number of force users Scourge has killed in his career should give you some pause, when trying to estimate his skill with a lightsaber and his abilities in the Force. And before you even object with something like "Well. Maybe those were weak or he just executed them." Nope:"When a Jedi grew too powerful or a Sith too ambitious, Scourge eliminated the threat. Conspiracy theories held that Scourge was a title rather than a man, for even pureblooded Sith are mortal. Allegedly, dozens of men preserved Lord Scourge's fearsome reputation across the centuries. These assassins, surgically altered to resemble Scourge, secretly replaced predecessors who fell to old age or violence. However, the Dark Council knew the truth. There was only one Scourge, his life prolonged by Sith alchemy, and his battle prowess enhanced by the Emperor." - SW:TOR Encyclopedia, p.94
Emphasis mine.
You may want to think about what kind of person Vitiate would consider "too powerful" and "too ambitious" in order to send the Wrath to kill them. There is a reason why even the most powerful members of the Dark Council didn't mess around with Scourge: Because he killed those kind of people in combat and did so for 300 years without fail. This is why he has his "fearsome" reputation, that even scares the most powerful individuals in the Empire. Hell. It is even mentioned outright, that Vitiate enhanced his prowess in combat specifically.
Scourge killing tons of individuals Vitiate thought grew more powerful, individuals with amazing combat feats is something beyond Caedus. I'm not sure what argument anyone can make for Jacen
Yiz, he iz only >> Slayers who r >> Knights, while 10+ yearz pre-prime, he contended with a luke who waz wekened, bcz of a wound, which onley hindered him, after Jacen hit him, and he only stomped Kyle whail hindered, but kayle was weakend bcz of his team mates, which only saved him from getting blitzed