You can argue all you want about the definition or justification of murder. There has certainly been plenty of blood spilled.
I see the WoL as an exterminator. He projects power in a very specific manner. Others tell him where to do it. He assumes the reason is just. Maybe he cares. So far the public is on his side, but public perception can change easily, and the WoL does not have power in the political arena.

He is used as a tool. There must be some concern from his handlers about how powerful he grows, and whether it will eventually bite them.
But now he is also a resource. Since the revelation that the echo can be transferred, two separate scions have told him to his face that they wished they had his power, so they could act on their own agendas. Maybe the WoL is and always will be "good", but corruption can grow anywhere. Feelings of powerlessness and envy can poison even the Scions. In Lyse's case, she is under way too much pressure in a position she is not qualified for. I think the WoL needs to watch his back and his "friends".the political arena.