As for Arya, the girl is deliberately and willingly seeking employment as a professional assassin! No matter what mendacious tale of mercy or justice the Faceless Men use to dilute the unsavory truth of their occupation, they commit murder for money. Arya knows this, she was raised to hold proper values, and she still pursues a career with the Faceless Men in spite of that. You can make all sorts of arguments about how her losses and harsh experience is driving her to that, but the reasons why a person's character are formed in a certain way have nothing to do with whethr or not they are good or evil. They are good or evil based on their actions and intentions, not on what experience causes them to see evil deeds as an acceptable means. And, too, she murdered Daeron or Dareon or whoever the singer from the Night's Watch was. She was not in the Seven Kingdoms, so their laws do not apply. She is not a bannerman or titled noble with a responsibility or right to uphold the laws of the Seven Kingdoms, no matter what she claims in her assertion that Arya Stark did the deed. Plain and simple, she committed cold-blooded murder, for no genuine reason. He was no threat to anyone, least of all Arya herself, and there is simply no excuse for killing him. This proves that Arya is not simply in denial about the reality or actions of the Faceless Men - she is perfectly willing to commit murder and take lives for which she has no good cause.