Her knighthood was used to Irene, but the average person was not. As the first of her kind, she figured she should have expected as much.
As much as people's glances were enough to grate Irene, they were never outright rude to her, so she never demanded they fix themselves. Even if Felix gave her permission to defend herself as she saw fit, she was hesitant to draw more attention to herself.
However, it was clear that wearing armor was a different story. Knowing she was a knight made people keep their mouths shut. Without it, she merely looked like a rough village girl.
When the reeve doubted her merely because of her gender, she had no choice but to keep moving on, or she was certain she was going to snap at him. It was almost lucky they faced goblins shortly after because then she could take her irritation out another way.