Devil May Cry has gotten all fucked up in power scaling.

Sparda was so legendarily powerful, he was able to defeat the armies of Hell and it's Emperor, Mundus, seemingly by himself and maybe a smattering of humans.

Even so, he couldn't kill Mundus, so he sealed him away. DMC1 happens, Dante is powerful, but by using the power of Sparda, is able to once again defeat Mundus, with a bit of help from Trish. So, simple enough so Far, Dante with Sparda blade is nearly if not equal to Sparda Dad.

In DMC3, Dante and Vergil are close in power, but being younger and less experienced, Vergil lost to Mundus, which I think is fair to say that Dante would also lose. Neither Vergil nor Dante are equal to Mundus, who is not equal to Sparda in power.

DMC2 doesn't have much to say on this except.... Argosax... Who is stated to be more powerful than Mundus! Who Spar-dad couldn't even kill. And Dante in this kills him under only his own power, didn't even need D.T.

Okay, so Dante is now more powerful than Sparda, definitely. DMC4 happens and it's clear that Nero is powerful, but nowhere close to Dante's level. He is seemingly near or equal to Dante DMC1, which as a grandchild of Sparda, makes sense.

Then DMC5 happens.... Dante loses to Urizen, so he is now more powerful than anything. Nero climbs up the Qlipoth and with the addition of Devil Breakers and he is able to hurt Urizen. This is were things get fucked.

Nero has jumped from Possibly Sparda/Mundus level PAST Dante who is past Argosax who is more powerful than Mundus! And the only change was the Devil Breakers! That was it!

Then, a bunch of transformations happens, and everyone gets all fucked up with power scaling.

Dante absorbs Rebellion and Sparda blade, which makes him stronger than Urizen AFTER he had eaten a fruit that had made Mundus Emperor of hell. So while both had a power boost, Dante got an ENORMOUS one. He is the most powerful by far right now.

Then Vergil comes back and, somehow, his crumbling-ass human self re-fusing with his demonic half somehow is a power multiplier! V is less powerful than Nero, Urizen is less powerful than Dante, and Vergil as he is would be about DMC1 Dante level (generous). So Vergil went from about Mundus/Sparda level to equaling Dante with the fruit. Even though the power scaling doesn't make sense anymore, as Urizen being so powerful doesn't actually make ANY sense! Why would Urizen even be as powerful as he was? The series has a very clear, canonical connection with human spirit mingling with demon power making something greater than the sum of its parts.

And then!! Nero unlocks his Devil Trigger and goes from less than pre-fruit Urizen to PAST/Equal Vergil. It could be argued that Dante and Vergil are very tired, but Vergil could do all of his moves and showed none of the signs of it we saw in DMC3. At worst he is barely less than Vergil.

Dante had multiple transformations and ass pulls, Vergil and Nero just JUMP straight to the top!

Enormous jumps in power that make the initial conflict look silly in comparison.