Kinda off topic, but I have to ask: Where do you get this stuff, G4E? Like the stuff in RPGT E-war, is it your own mythos or is it inspired/taken from actual media?
On topic: As for the suggestion, I my main concerns are a few things: First, it does seem similar to FRPG or SSRPG. There have been a few topics that deal with demons and the like, and the concept is essentially the same.
Second, you seem to put a lot of focus on the demons, but not really as much on the humans or the Enforcers. In my opinion, if we look at Darksiders, the thing I liked about the side of Heaven in the game was that they were basically one with technology. It gave an interesting take on the whole concept of angels, seeing as their wings were basically robotics, they had futuristic weapons, and were very organized and tactical. It was a serious contrast to the demons, who were chaotic, violent, and very primal, using mostly natural weapons (Claws, teeth, etc) and the very basic of weapons, and the occasional magic.
Giving the Enforcers bows and arrows kinda ruins this aspect. Its essentially making a Heaven VS Hell kinda thing, which can be replicated in other RPGs, with demons fighting various other things, but replace "blast of holy energy" with just "blast of energy"
You could, actually make the humans futuristic and such, which would actually give them a fighting chance against the others, taking the place that the Enforcers would fill (Again, if we are comparing it to Darksiders). You see, you have to give motivation for players to use each side, rather then just stick to demons and such. You've explained that the "evil side" includes demons, horrific beasts, and undead. You said the Enforcers only get angels and holy beasts. While the holy beast concept might be interesting, what, exactly, do you define them as, or the angels for that matter?
Traditionally angels are basically winged humans, and in this case, wield medieval weaponry. Booooring
And you explained even less of the humans. Honestly, this idea has potential, but you can't just reuse the concepts of other media, even if the details are completely creative. Like, demons being...demons, but fighting against battle suit wearing angels, or mech-armed humans. The more originality, the better, but that doesn't mean things need to be overly complex.
Rant over. For now.