Faerin Lothar is an important character in the War Within. Presumably a distant relative of Anduin Lothar, she lost an eye and an arm at a young age, but she has replaced her arm with a special shield. We learn more about this interesting prosthetic in Hallowfall's main questline.
The Arathi of Hallowfall are survivors of an expedition that was sent out from an Arathi Empire fifteen years ago. At the time, Faerin Lothar was still a child, and she snuck aboard one of the expedition's ships. Disastrously, the expedition's entire armada was caught in a terrible storm. Many died, and those who survived found themselves stranded in Hallowfall with no way to return home. In a conversation about the Light, Faerin tells Anduin that she lost her eye and her arm because of her decision to join the expedition — it seems she may have sustained these injuries in the storm.
Rather than replace her missing limb with a prosthetic arm, Faerin has had a shield mounted against the shoulder instead.
During Hallowfall's main questline, Faerin introduces us to the armorsmith who designed the shield — Raen Dawncavalyr. Raen offers Faerin a new prosthetic arm, but Faerin declines — preferring her shield. However, she does ask Raen for an improved shock absorber, which Raen agrees to work on.