It seems as though a few here are glossing over some background lore that's been given throughout the chapters. I made a post a few pages back discussing my thoughts on how the story might develop which can be found
here. The tl;dr of it is that
Balthazar is most likely the main antagonist and is using Taron as a puppet.
Early on in the prologue the angel Castiel warns MC's parents of Balthazar, and if MC ends up turning to the dark side that he will be forced to "intervene". The angels consider Nephilim a sizable enough threat that if they go on a murderous rampage that they need to take action.
Balthazar definitely became powerful enough to avoid death, what happens if he manages to corrupt the MC enough and supercharge him as well?
Additionally, dark powers are specially curated towards killing or inflicting immense amounts of pain on a victim while light powers seem to focus on non-lethal takedowns of threats.
BuuPlays is making an intentional design - and story - decision when developing the powers for MC.
The main issue seems to be the question of: what happens if you gain a mix of dark and light powers? Chances are that this might come down to a check of whether you leaned more towards the dark or light path and locking you into that morality for the finale.
The dark path will most certainly see the MC either teaming up with Balthazar and slaughtering the entire human race - or even becoming something worse than him. The light path is a bit more complex, especially when considering that if Taron is meant to be the main antagonist instead of Balthazar that he is severely outclassed by a literal demigod. Either way, the epilogue will definitely be drastically different depending on which morality you favored.
That is the entire point of the dark path. You have an MC with no humanity that sees the other races in the same way that we see ants. He has no compassion or empathy, he does whatever he wants whenever he feels like it.
I know that there is way more to your post, but the light path is intended to be forgiving. Have you noticed how the powers you get from that path typically involve non-lethal powers? Think of Aang from A:TLA and how his character was written (especially in the finale): a boy who was gifted with insane powers that could either be used lethally, or used to disarm.
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I'm separating this part from the content above since this is mostly about the LIs. There seems to be a clear distinction between LIs intended for a dark path, those intended for a light path, and some that fall in between. A clear example of a light path exclusive LI is Sylph due to her race, while Selena is an excellent example of a dark path oriented LI due to her enjoyment of inflicting pain on those she thinks deserve it. Eliza falls somewhere in the middle as she doesn't shy away from killing others (whether they deserve it or not), but doesn't approve of outright evil acts (i.e. killing innocents).
A consequence that may come in the future due to which morality you favored may result in some LIs forcibly ending their relationship with the MC similar to the ones in Fallout: New Vegas or Divinity: Original Sin 2. I wouldn't be surprised if Buu uses Eliza to punish players who favor a dark path playthrough since the dude becomes a murderous psychopath. Seriously, being able to outright kill innocents is not something I thought I'd see in the AVN space (thanks for that awful scene btw...).
To those who made it down here: I apologize for writing such a lengthy post. Hopefully it encourages some more discussion within the thread since this VN is a gem.