Ok, so now that I slept and got over the ending, I'll give my 2 cents on it, please like if you agree.
So, the build up to the fight is great, because it raises questions about human nature and how we should work it out in order to achieve peace, Vergil represents Thomas Hobbes, that believes that the human nature is corrupt and evil, so in order to achieve peace and maintain order, we need a solid state directly acting upon our society, and he calls that the Leviathan, while Dante, in the other hand, represents Rousseau, that believes that the human nature is good (and exemplifies with a child's innocence), and that the state of society that may or may not corrupt them. This is a GREAT discussion and I love that it's being raised by a videogame, huge props to Tameem for that.
But then comes the after fight ending and throws it all away when Dante stabs Vergil like a mad man, Vergil admits defeat and Dante becomes our protector and fanboys and fangirls have nerdgasms with him and Kat possibly becoming a couple, it's just too bland, too straightforward, in a way that it invalidates the discussion beyond "#TEAMDANTE" and "#TEAMVERGIL", so what I'd do would have a physical object of their conflict, like a power core Mundus uses to control society, and Vergil wants to take over that (his very own Leviathan) to maintain order and peace for mankind, while Dante believes that humans will end up just fine and we don't need an opressing power guiding us, so he wants to destroy the power core, then their conflict happen, they fight, and both during and after the fight Vergil gives GOOD REASONS for his point of view, and maybe even a twist involving humans in what happened to their parents, making Dante question himself. Dante beats Vergil and gets to the core, and he's hesitant, he's not so sure anymore about what's the right thing to do, and then we have this open ending (or they can end it with Dante destroying the core, but make he question himself first!). The way I see it, the best way to make your players wonder about the conflicts you proposed is to have the character they impersonate question it himself. Dante not even thinking twice about it renders all the discussion useless. Had he doubted himself in the end, even if he did destroy such power core (just like stating that he doesn't know if he did the right thing or whatever) you will raise this great discussion about human nature, what defines a dictatorship and the value of freedom, which would make for an amazing ending with months and months of discussion (that wouldn't even achieve a final answer) over the themes themselves, instead of just the superficial "what did you think of that scene when Dante stabbed Vergil??".
In the end, it was still a great ending if you consider all the build up as part of the ending, but if you just consider the post-fight scene as the ending, you'll get something very bland and disappointing, lacking the final "punch".