Actually, I kind of feel Eowyn was wildly, wildly irresponsible in the books. She abandoned her obligations, obligations her uncle and her brother dutifully observed, risking life and limb in a war for the entire world. ALl she was asked to do was live a life of relatively opulent comfort and safety back at her family's holdfast, to oversee her people as a steward to the house. I don't think she really deserves as much praise as she gets. She was basically acting like a child, pouting and stomping her feet and then when that failed she flouted the rules to SAVE HER PEOPLE entirely and rode off, the last heir to the Horse Lord legacy. Responsible kid. She basically mooned her uncles' sacrifice, because...well she just wanted to fight...even though she's never, you know, fought before, hasn't demonstrated any seasoned skills, or left any confirmable government behind her to mind the kingdom. She just left.
She's really a terrible character if you give her any thought.