"The Roaring Fraud/The Frauding Knight" is a term used for the eponymous Roaring Knight from Deltarune.
Despite being an incredibly difficult fight even by secret boss standards, the Roaring Knight has gained a reputation as a Memetic Loser in the fandom. This stems from the fact that it has to force a cutscene once its health gets low enough in order to win, which is fueled further by the interpretation that Kris in the ensuing cutscene bails out the Knight from being defeated too early. This, plus Susie's boasts as seen above, has led to it being characterized as a coward who isn't as powerful as they pretend to be, especially in comparison to Susie.
But are people and Susie right about them? Well, it's more complicated.
While it's pretty clear the Knight was kicking the Deltarune Trio badly, one has to remember that Susie was able to hold her own until the Knight used their cutscene-ending slash to incapacitate them. Plus, Kris is seemingly working with the Knight and holding back.
However, after the fight, it uses some rather shady, dirty tactics, and one could see them as cowardly moves:
When the Fun Gang confronts them at the end of Chapter 4, Susie believes that, since they were able to leave the Dark World from Chapter 3 and drag Undyne with them all the way to the Dark World in the Shelter, they must at the very least be a Lightner to be able to do so, and thus the source of their power must only exist in the Dark World. Cut them off from the Dark World, and they should become a powerless Lightner—and thus, by sealing the Dark Fountain first, they'd not only expose their identity but also take them down then and there. The Roaring Knight doesn't even give the group a chance to see if she's right, immediately summoning a Titan as a distraction and fleeing in the confusion.
If you aren't blown away by the Knight immediately, you can see several signs that Kris is sabotaging their team's efforts.
It's easy to miss, given that everyone's damage to the Knight is already reduced, but by default Kris' is lowered further by half. However, it will be doubled for each of Kris' teammates knocked out, thus making it higher than normal if Kris is the last one standing. Evidently, it's hard for Kris to hold back against someone who just viciously beat their closest friends.
When the Knight knocks out Susie or Ralsei, they get a special status preventing revival. Kris just goes into negative HP as usual, suggesting the Knight is holding back against them in turn.
The most blatant sign is only shown if the player somehow manages to get to the end of the Knight's incredibly difficult boss fight without taking a single hit. When this happens, Kris will cough while the Knight slowly tilts their head—a seemingly wordless signal between them that the SOUL is just too skilled to be defeated by attrition alone, and that they need to throw the fight now.
The Knight is seemingly untouchable and a Hopeless Boss Fight... but it is possible to survive and continue dealing damage until you get its HP below a certain threshold. While it's possible that it glitching out might've been an act to get Susie's guard down by pretending to lose, Susie did damage the Black Knife, showing that the Knight and its equipment can be damaged with enough effort.
This tendency extends into Chapter 4. When encountered in the Dark Sanctuary, they waste no time knocking Kris and Susie down into the depths of the Dark World, destroying the stairs from the atrium to the Fountain in the process. They reappear several times to rain down a Storm of Blades in an attempt to impede the heroes' progress. And when they're apparently cornered at the end of the Third Sanctuary, they dodge Susie's attacks with ease and create five Dark Fountains to summon a Titan.
However, "winning" the fight will show Susie and Ralsei being defeated in a single swoop while their guard is down, from an attack that doesn't even display visible damage. Likewise, their surprise attack against Tenna (which they evidently did bare-handedly, given the twin slicing attacks that tore off his arms) deals upwards of 5900 damage, further showcasing that the Knight didn't need to put 100% effort in against the heroes when fighting them.
"Winning" the battle with it in Chapter 3 by surviving its final attack does force the Knight on the defensive and to seemingly retreat. Then Susie and Ralsei are slashed from behind while their guard is down, and the Knight makes Kris kneel, effectively having the same result as losing the battle. On the bright side, you get a sick weapon and a Shadow Crystal to boot out of it.
All in all, once it fights us, the SOUL, and the Fun Gang afterward, it remains on the defensive, attacking from afar and never rematching us again—escaping during the confusion it causes—along with Kris deliberately stopping us. Plus, the fact that similar entities like Asriel can be defeated by us also plays a role in this idea.
