I would assume this is an alternate spelling of Arminel. According to E. G. Withycombe's
The Oxford Dictionary of English Christian Names, Arminel is a woman's name which was mostly confined to county
Devon in England. The earliest example the book gives is from a woman living in
Devon in 1797. Withycombe says that Arminel "looks like a diminutive of Armine", itself a French feminine form of
Armand or
Herman, but the way she phrases that it seems like it's just her educated guess as to the origin.