One aspect of Arwen that sticks with me to this day is the dresses she wears, which are a far cry from the muddy, travel-worn clothing worn by the other characters most of the time.
Each is beautiful, ethereal, and ornate in its own way and speaks volumes about the state of her character, even when the story itself doesn’t have the time to devote to her.
Having her come to the rescue, clad in her signature blue, shows that this version of her is no less a part of her than anything else the audience is about to see.