From season 1 where they battled their most powerful enemy, a level 3 if I'm not mistaken, they showed some growth. They adopted psychokinesis to their fighting style and it improved it. Season 2 showed very powerful enemies and the plot really navigated the story really well. From revenge to salvation, it shows that people despite succumbing to a blinding path of revenge have some humanity remaining deep within their soul and that helped the ML in overcoming their dangerous situation. The new member elevates their overall capabilities since he can detect evil spirits despite not having the territory.