Even Zev.... although his change is going from 'I'm happy to kill people' to 'I'm happy to kill people for you'... so not much improvement.
I'm not excusing Zev but comparing his case to Velanna's is nonesense. I love both characters so very much (Velanna a tad bit more than Zev but,):
Zevran was sold, tortured, and forced to do these tasks. Being sold into the Crows meant you have to comply or you die. Zevran had these images and ideas forced into him as a kid, he was abused from since he can remember. The only thing he had of his childhood was ripped away from him and he could not afford to be "morally good". Hell, he wanted to commit suicide because of all the struggle and because of what happened to an innocent girl, that is when he realized the weight of what he did to her.
Velanna did it out of spite. She was so brutal and so toxic her own clan was disgusted enough to kick her out. She did it because she assumed Humans had to do something with her sister, so she killed possible merchant, travelers, for no reason other than "they might have my sister".
How can you compare the struggle of a forced Assassin to a woman who chose to kill innocents? Hint: You don't, one has a choice, one doesn't.
The others, I can't say much for. Everyone has a sense of grey morality, that's what I love about DA.
I hope Velanna comes back because I've heard out Wardens might, so maybe she will be intertwined with that?