She's worse than she ever was under Marjolaine or Warden's crappy influence.
Exactly, Hardened Origins Leliana, just opened up and accepted that she was a bard. She dropped the shield she built herself in the Chantry because she didn't want to be like Marjolaine but Hardened Leliana just accepts that there was a reason for her being like Marjolaine but she could still love. Because there was still good things in the world, good people. The Warden, Dorothea/Justinia, friends she made in her journey with the Warden.
But Inquisition Leliana. After 10 years of just going out and being a operative for the Divine. She probably killed people who she didn't even talk to. They could've had a family but she probably just went up to them gutted them and left. Her justification being that Justinia had her do it for a good cause. For Good people so that made her good as well. Plus it helped cement her belief in the Chantry as well.
She lost good friends along those 10 years. (not spoiling that.)
Then the Conclave happened, Justinia is killed and her faith is all but crushed. She really has no more friends since she hasn't really talked to them in years. One of her best friends is murdered and now she is questioning everything. She sees how ruthless the world is and she sees that as a sign that there is no good. Or if there was good, all of what was good for her is dead. (Even the warden if the warden is dead in a playthrough.) She then lets this be the reason for her to become ruthless. Even Varric states she never leaves her work, she is "Starting to twitch" You can bet Leliana is depressed, she hides it but exposes it at Haven. Claiming it was weakness and she shouldn't have shown it.
The Inquisitor is the final straw on who she ends up being. Either being the example that what she thought good in the world isn't dead, that it isn't all gone (unhardened, telling her not to waste life.) or Just cutting the rope/ pushing her over the edge and just finally cementing her fall into something worse.
I mean seriously? Some bard is saying some mean things around towns and taverns. Lets shut them up by cutting their tongue out. Don't you think that isn't going overboard. Wouldn't it be better to either slap them on the wrist or just do what Cullen does and just let them be.
I'm really surprised they didn't have some conversation where Cullen who has gone through his darkest times and emerged better. He spent 10 years of always being angry, hating mages and just not being himself. He definitely had PTSD after the torture and horrors the demons and abominations put him through in the Circle. Why not have something where Cullen tries to talk with Leliana, try and help her get through the Trauma and the loss?
Thats why I will always go unhardened Leliana in Inquisition. She is borderline psychopath with Hardened. Some people even are saying that hardened Leliana has the potential to become a villain in some ways. I actually agree with that. Seriously Natalie was a friend and without hesitation because Natalie was misinformed by a grand cleric she slits her friend's throat... WTF?
What is stopping her from turning on the Warden if down the road, The Warden tries to advise Leliana on a decision (as the divine.) that they shouldn't do something. But Leliana sees it as a threat? Worse situation she could kill the Warden. Best case? She ends the relationship, tells them to leave forever. And middle? Probably throwing the warden in a dungeon somewhere.
Sorry, Rant... There is so much hope for unhardened Leliana. I see Hardened Leliana kinda like Darth Vader. Fallen to the dark side but possibly in the end could somehow redeem herself. If she isn't horrified by the things she has done by then.