That's not why Darkness made the contract. Santa wanted to kill Makima, Darkness only attacked her because she got in its way. Darkness made the contract for Chainsaw's heart, and while I can't know its intent, I'd guess it wanted to get rid of the one thing that can permanently kill devils.
My thought was that he wanted the heart in order to lure out Makima, as is implied here.
Your interpretation holds value too but in either case, Darkness
did try to kill Makima and failed, that much is undeniable. Wheter or not the contract was made with that goal in mind, is up for debate and im not interested in arguing that further.
Also I don't know what being in darkness has to do with anything, I don't think it's said that Darkness is amped in the dark,
It's been repeated multiple times throughout the manga that War needs Chainsaw as a weapon to challenge Death. That's the entire plan, it's why the Chainsawpocalypse was started. Mentioned as recently as chapter 191, at least. Yoru needs to use Chainsaw to have a chance at victory.
Chainsaw is needed in order to "erase" Death. Its not ever stated that CSM is needed in order to physically amp War Devil to even have a chance of fighting Death like youre insisting. Similarly to how characters could fight Makima and even kill her over and over but they didnt have the power to "erase" her.
Her words currently still stand, starving wasn't the cause of weakening, she just said the devils under her control couldn't use their full power.
Her words were from back when she was pretending to be Fami. But when we see how her powers actually work, its never stated/implied that it "weakens" them.
Also we later saw Fakesaw literally cut Yoru's "bang" in half. Makes 0 sense if that is his "weakened" form, it barely makes sense he can do that at full power.
Give Falling a second too, there's no reason to think she's dead. She's come back from mincemeat. And she's had plenty of times where she didn't instantly heal despite being able to. You're counting your eggs before they've hatched.
I know what youre referring to (the time Fakesaw cut up Falling) but im pretty sure shes dead. In this case we can literally just wait a chapter or two to see so no point arguing.
I think Yoru has already proven herself above any Primal by the way she handled Falling. She wasnt even paying any form of attention to Falling, the last attack Falling landed was because Yoru was staring off into the distance crying about the Nuclear Weapons Devil instead of looking at Falling. I really think running any defense for the Primals here in comparison to Yoru (who as you said, will only get stronger once the metaphorical and literal Nuke is obtained) is setting yourself up for being wrong.
Anyways nice discussion but i got a Blue lock chapter to read now. Until later o/