I think the thing that always frustrated me as far as the Dark Willow storyline and accessing Willow's culpability, is the fact that there's a big double standard that exists between not holding her accountable for her actions and forgiving her a bit easier vs holding Spike, Faith, etc. accountable for their actions and not being so willing to forgive them quite as much or even a little bit of all.
Case in point:
Willow flays a man to death in the name of love. Now, said man was a horrible person who did horrible things and killed the woman that she loved and tried to kill Buffy. I get that, it's not lost on me at all. The thing is, it wasn't Willow's place to play executioner no matter how much she was grieving, no matter how addicted she was to the magic, no matter how much she wanted revenge. It wasn't her place to take it. And honestly, I feel like she didn't have to deal with the consequences, as she should have.
Thing is, she had a soul very much in tact, even if it was conveniently bathed in dark magicks, it was still there and she should be held just as culpable as anyone else would be.
Vs another case in point:
Spike does what he did in Seeing Red and a number of different evil no good bad nasty little things while completely soulless and he's still held very much accountable for what he did, quite hated by some, and definitely not very forgiven by other's. And the difference between him and Willow is one damn soul.
And I've seen some argue that it does matter and some say that it doesn't, well in any case...one murder was done with a soul and countless other murders were done without a soul. Either way, none of the murders should ever be okay.
I guess I always felt like because Willow had a soul when she actively and willingly killed Warren, went through the trouble of actually seeking him out so that she could carry out her plan of killing him, was worse because she had a soul. Buffyverse has taught that having a soul matters, that it's what determines the moral compass of someone or the thing that inhabits it.
Another thing, she is the one who decides to bring Buffy back from the dead with some wicked mojo, that she has to deceive her friends in a way to get them to go along with it and she purposefully waits until Giles is out of the country where he can't know a thing about it and she leaves Spike out of the loop. I believe that she did those knowing that a.) Spike would try and stop her or like he said, if there was anything of Buffy in that thing that came back all wrong he wouldn't let her kill her, and b.) knowing that Giles would definitely disapprove and would actually try and prevent her from going through with it.
In any case, this is completely selfish and on the other hand if I put myself in her shoes, I can also understand why she would so desperately want to bring her friend back. This is Buffy we're talking about, she's saved the world a lot, saved their asses more times than all of them combined can count, and she basically just kicks ass a lot. The world needs her, so who is Willow to deny that. Plus, Willow needs her too, she needs her best friend back because she loves her and she wants her there in her life. It's perfectly understandable, because nobody really knew where Buffy was when she sacrificed her life.
They were all under the impression that she was trapped in some hell dimension and Willow along with the rest of them could not live with this, so hence the spell. I don't know that I can honestly say the spell shouldn't have happened, because S6 is one of my favorite seasons. (Probably a minority here, on that one.) But, at the same time, I feel like Willow had definite culpability in the deceiving and I don't know that I like the fact that she basically u-surped Buffy's decision to carry out her sacrifice at the end of The Gift.
I think, I'm a bit more willing to forgive that, than I am to forgive her killing Warren.
Then if we delve a bit further into all of this, there's the spell in Tabula Rasa where she wipes their mind, and then again when she uses magick on Tara to make her forget the argument that they had.
I feel like I also need to say that I care about Willow, as a character. She was always one of my first immediate favorite's and she probably always will be. But, even I as a fan, can see that there were some discrepancies that have been over-looked or haven't appeared to be necessarily fair when we're talking in terms of whom we're holding accountable and for what atrocities they're also being held in contempt for.
In short, the double standard bugs me as a Willow and Spike fan, at heart. I love both of these character's and they've both made big mistakes, but I guess all I'm saying is if we're going to hold one responsible then why not the other as well?!