its said that one does not AIM to kill in the tournament to become King/Queen, but Kurogh was able to get away with it and yet Athrenna did not kill him when she knew he was nothing but trouble. If there’s consequences for killing then why didn’t Kurogh fall to them? If there aren’t then why didn’t Athrenna do the greater good and spare her people of his tyranny? Even if he is a great tactician, he was still a danger in her eyes

Because Athrenna valued her people’s laws and morals over what she personally thought was right. You do not kill your own, that is the utmost sin. Even if she could get away with it, she wouldn’t purposefully kill Kurogh or even send him to his death. Mind you, she only saw him as an unfit king, she had no idea of Malefor or what Kurogh would eventually be responsible for. So to her, killing someone because she thought he’d be a bad king is petty and beneath her. She was too strong for him but she wouldn’t win anything if she just killed him, that’d just be murder and another Kurogh would take his place. You kind of have to see it from her point of view, not what we all know now. 

Athrenna was wise and the ideal Queen, but she still didn’t think she was above the laws or could just get away with things. She obeyed every law with an iron talon and cold calculation, despite being warm and motherly to her people. When she was Queen, her major concerns were what was causing the decline and destruction of the other ports, cities and villages of the Kuros and how to keep her people from panicking. 

~Weird Hyenas