florapkgx's list "Irish Mythology Names" of 4 great name ideas: Ferdia - Sadhbh!

Irish Mythology Names

Ferdia

Popular in Ireland, though not as popular as its spelling variant Eimear, Emer is a mythological name, associated with the legendary wife of the warrior hero Cuchulainn. She was said to possess the six gifts of womanhood: beauty, voice, speech, wisdom, chastity, and needlework.
 
While the exact meaning of Emer is unknown, one theory is that it means "swift" or "quick". 
 
Pronounced as EE-mer, this form of the name was most popular in 1983, when nearly 200 girls received the name, placing it in the Top 50. A more recent year saw it given to less that 2 girls, however.
 
Other forms of the name include Eimer and Éimhear (said as EH-ver), along with the Scottish variant Eimhir (pronounced AY-veer).

Emer

Grainne is the Irish form of the name often Anglicized as Grania. It was the name of the ancient grain goddess and also of the fiancee of mythological hero Finn McCool and lover of Dermot, who was a heroine of the seas. 

In the past, the name was anglicized as Grace, as in Grace O'Malley, Ireland's pirate queen. Grania is a phonetic spelling.