Vergil throws his Summoned Swords around without any motion involved. It's already Simple, yet Awesome in gameplay (as his ranged attacks can be used even while performing melee combos), but this also means that he can kill demons while standing completely still. This is made more obvious in "Heaven or Hell" mode where enemies die in one hit, but the cinematic Hit Stop effect added in DmC and DMC5 makes it more awesome; Vergil can retain his stoic expression and kill enemies even without lifting a finger.
Pretty much any time Dante shows up to destroy the warning screen is awesome. Special mention to the moment in the 3rd game, where Dante kicks the camera.
Finishing the games on the hardest recurring difficulty mode; "Must Die". The player is then rewarded with the Purposely Overpowered "Super" costumes/perks that grant infinite Devil Trigger gauge alongside other character-specific effects. These are a Bragging Rights Reward by that point, and if you don't mind the score penalty while using them, you can still have fun exploiting the overpowered mechanics such as constant Max-ACTs for Nero, or starting (then immediately ending) the minor battles with Vergil's Judgement Cut End.
Though it's just a cameo, one of the endings in Capcom Fighting Evolution shows Jedah conquering the world and laughing evilly... and then, it proceeds to show Dante ready to challenge him.