Balla is a perfect verb meaning “soaked.” Damʿī, “my tears,” is its subject, while miḥmalī, “my sword strap,” is its direct object. The final first-person yāʾ on each noun marks relation to the speaker.
Ḥattā introduces the endpoint or result: the tears continued until they even wet the strap. Reversing subject and object would distort the meaning, as though the strap had soaked the tears.
The strap is a concrete detail, making the grief more vivid than the abstract statement “I wept greatly.”