What does Darcy mean?
Two distinct origins: as an Irish name it anglicizes O Dorchaidhe, from 'dorcha' meaning 'dark', giving 'dark one'; as an English/Norman name it is the aristocratic d'Arcy, a locational surname meaning 'from Arcy' in Normandy, with no 'dark' sense. Both are genuine; flag which is intended.
What does Kane mean?
The 'battle/warrior' sense comes from the Irish Ó Catháin, from 'cath' (battle). Flagged: Kane has several unrelated origins - Hawaiian 'man' (and a deity), a weakly attested Welsh 'beautiful', and Japanese readings - so only the Irish line carries the warrior meaning.