Mabel

Amabilis of Riom (died 475) was a French male saint who logically would have assumed the name Amabilis upon entering the priesthood: his veneration may have resulted in Amabilis being used as both a male and female name, or the name's female usage may have been initiated by the female saint Amabilis of Rouen (died 634), the daughter of an Anglo-Saxon king who would have adopted the name Amabilis upon becoming a nun.
Brought by the Normans—as Amable—to the British Isles, the name was there common as both Amabel and the abbreviated Mabel throughout the Middle Ages, with Mabel subsequently remaining common until c. 1700, from which point its usage was largely restricted to Ireland, Mabel there being perceived as a variant of the Celtic name Maeve, until the name had a Victorian revival in Britain, facilitated by the 1853 publication of the novel The Heir of Redclyffe by Charlotte M. Yonge…