Really?
Cause I honestly see no difference in their power besides the fact that new Vergil is different character wise from old Vergil and new Vergil moves around more then old Vergil. Both Vergils are roughly around the same age, and their's no differentiation of power between the two because new Vergil was created to be at the same level as old Vergil, just as new Dante was created to be at the same level as DMC3 Dante. Regardless of universes, both versions of the characters were created to be at the same power level. So I honestly see no difference in their power, thus why I say if new Dante could defeat new Vergil, then he could also defeat old Vergil as well.
>no decent healing factor
>nearly killed by Donte with a single stab in the chest
>no surviving by a sword nearly cutting him in two parts and still proceeding to fight the Prince of Darkness alone after falling from a very high fall
>no demonstration of mastery of his fighting style
>let the fights be done by his brother instead of helping and acting like a warrior
>no slicing the head of a probably rival of his own overpowered father to pieces in a matter of seconds
>no slicing one demon to pieces without even turning his head to see what he is hitting
>no devil trigger that boosts all the natural abilities of a hybrid
>son of a demon that was caught to be tortured eternaly instead of a demon who faced alone all the hordes of hell to save humanity
Yeah, they seem pretty equal to me too.
Like i said before, the original universe has much more fantasy and strays more from reality than the new one. For the sake of a narrative that has it's "feets on the reality" they had to make more believable and human characters. That's why the demons in the original DMC are much more fantastic and have all kind of powers while in DmC they are for the most part (except Mundus, besides?) gigantic or just ugly beasts trying to smash or cut Donte.