Why was the hand of the female Companion Nusaybah al-Maziniyyah cut off, and who defended her?

Umm Ammarah, Nusaybah bint Ka’b, was a venerable female companion from a noble family. She witnessed the Pledge of Aqabah, Uhud, the Pledge of Ridwan, Hunayn, and Yamamah. Her husband was Zayd ibn Asim, and her two sons were Habib and Abdullah. Habib was killed by Musaylimah al-Kadhdhab for refusing to testify to his prophethood, and Abdullah was the one who narrated the manner of the Prophet’s (peace be upon him) ablution, and he killed Musaylimah on the Day of Yamamah. Nusaybah remained steadfast with a few others on the Day of Uhud, defending the Prophet (peace be upon him), whereupon he supplicated for her and her family for blessings and mercy, and that they be his companions in Paradise. On the Day of Yamamah, she sustained twelve wounds and her hand was severed. Abu Bakr used to inquire about her and visit her. No story has been found regarding a woman ridiculing her.