So, this is up again, so as a guy who likes both quite a bit and has done extensive research on this matchup specifically I suppose I could chip in my two cents and look at what Dante and Ragna have to throw at each other (each will be respective):
More varied elemental/energy manipulation = More versatile and precise dark manipulation
Faster-acting regen + Royalguard Style = Constant self-healing from absorbed Soul Energy
Spatial Manipulation = Won't have a super notable bonus effect, Noel and Hakumen cut through space all the time
Minor Precog via Alastor = Sixth Sense
Mind Manipulation < Impressive, but Ragna's taken much worse. It would be a waste of his time and just get him to eat damage.
Flowery, elaborate fighting style and constant taunting < More direct, brutal combat fueled by rage. Dante's style would work well against many people, against Ragna if would just backfire.
Higher AP/Dura > Lower AP/Dura. This one's pretty self-explanatory.
Devil Trigger = Overdrive
Majin Form has two variants and is more potent = Unlimited Mode has no notable time limit.
Slightly higher experience/raw fighting skill and physical strength > While neither would be significant enough as edges on their own, together they'd probably add up. Usually physical strength doesn't matter all that much, but I guess if they get into an arm wrestling contest or something...?
Superhuman Willpower = Superhuman Willpower
Hundreds of kilometers < Planetary range
More versatile weaponry > A single weapon that can take the form of a sword, glaive, or scythe. Dante more or less has his own copy of the Blood-Scythe in the form of Sparda, everything else is icing on the cake.
Higher stamina > Immense, but not quite as immense, stamina.
Various barriers/defensive techniques < Ragna's are more generally consistent in their ability to block things
Miscellaneous methods of setting up combos = Trap/restraining Ars Magus glyphs
C-C-C-COMBO Breakahs = BARRIER OVERLOAD!
Miscellaneous powers in general (TK, for instance) as auxillary support = Exists outside of logic for miscellanous catch-all defensive ability.
So now I guess it's time to come down on the big deal-breakers here.
Dante: Time manipulation, for starters. Ragna can resist it, sure, but that's not the same as waltzing through a time stop, and depending on when/how it's used it could be devastating for Ragna's well-being (i.e. burst him down when he's closer to death before he can recover.) Of course, that's not even remotely a guarantee, but I'd say it is Dante's biggest asset he has to work with that Ragna has no specific answer to.
Also, Doppleganger Style. I feel it's been over-selled above, given the giant AoE of a lot of his attacks and the general experience he has fighting people like Jin and Nu-13 who throw non-stop attacks at people from all sides, but it's still a fairly major player in Dante's game if he hopes to win. What can it do?
A: Spare the real Dante some hits if used right.
B: Double up on his damage.
C: Increase his unpredictability.
Really, what can't it do?
And finally, Jackpot. Unlike the last two edges, whose effectiveness were mostly dependent on who is more able to think fast at any given point in time, this is more a very slim chance to just end the fight entirely, sort of an alt. win condition. I know it's sort of silly to imagine, but if it ever got to the point where Dante was hard-pressed/tired of trying to beat Ragna down, he could just go "Screw it" and try to blast Ragna into the Demon World like he did Mundus, and thus out of his hair. Last I checked that place was near impossible to navigate, especially for newcomers, and Ragna'll definitely have enough demons to preoccupy him while he's there so I don't see him getting out anytime within the year. BFR counts, yo.
Granted, with how choreographed the attack is Ragna has about as much a chance of getting hit by that as winning a lottery big enough to pay off his bounty and learning that Terumi died of a heart attack in the same day, but with how bad his luck is (plus Dante using it in conjunction with other abilities)... well, you never know, eh?
As for Ragna? Yeah, Soul Manipulation, obvious win condition is obvious.
I'll get this out of the way now: I do not believe Dante's soul resist is impressive enough to trivialize this aspect of Ragna's power. If anything, Dante's showings of "soul durability" are less than those of many of the Blazblue-verse's central players. Why?
Well, how strong is Dante's resist, exactly? We know it was able to keep him up and running through that Neo generator incident, and that was used to power the many-miles-high Temen-Ni-Gru, yeah?
Time for a comparison.
Arakune, a "strong soul" by all standards when compared to a normal person, touched the boundary for just a moment, and it nearly undid him entirely. That's why he's the blob-monster we see today.
Hakumen, on the other hand, lounged about in the boundary for a whole century or so before being spat back out, and he was hardly worse for wear all things considered.
We know it's a continual "erosion" type process, it's not like how we consider durability on this site. That being the case, it that time, even if we were to assume the "moment" that Arakune touched the Boundary was like 6 seconds or so, that'd be enough time forever half a billion Arakunes (or an equivalently strong soul) to turn into unintelligible mush.
Hakumen damn near no-sold this, and Ragna's soul shred still works on him.
Soul manipulation is sort of Blazblue's bread and butter, one would be hard-pressed to find a verse in their general weight class with comparable hax of the sort. That's why Ragna would in practice be such a dangerous opponent against Dante despite the previously mentioned AP/Dura disparaty, this is attached to basically everything he does.
On top of this, since the shredded soul fragments are converted directly into seithr through Ragna's drive, he's only going to get more and more powerful, both offensively and defensively, the longer the fight progresses.
...at the end of the day, I might go for Dante... except there's one issue: Dante himself, or more specifically his mentality. He's the kind of guy that would purposefully go easy from the start to give the other guy a fair chance, and at this point he's used to easily dominating just about anyone and anything in his verse. Against someone like Ragna, this'll just cause him to end up eating lots of damage at the start because he wouldn't in character go all out with his tricks and traps from the get-go (something that would infuriate Raggy to no end). Dante is, in other words, as much his own enemy as his actual enemies are. Ain't that why we love him?
It is still perfectly winnable for the dude, don't get me wrong, but I'll have to give a slight overall edge to Ragna. With how close it is though (I can see definitely see Dante winning 45-50% of the time), I'd be content just ruling Inconclusive overall and calling it a day.
P.S.: Sorry about the Great Wall of Texta, there's just a lot to consider for this one.
