You followed through with your attempt to disarm the supposed Ana however. As you neared her, she attempted to swing with the weapon she now held in her hands. However, her attack was clumsy, and though the Sword of Galas'nor would have been a dangerous weapon in the right hands, when she swung, she missed completely. Using that momentum, you reached out with your weapon, striking just so, and soon enough the sword fell to the ground; the disarm successful.