Somewhere -- maybe the St. Alexander's burial records at Rootsweb, perhaps, I stumbled upon a record referring to an "Ignatius" with similar data points. Still, at this point, I wasn't seeing anything. But then it clicked. Ignatius in latin, Ignace in French. And "Ignace" pronounced properly (Eeeg Nass) is a heck of a lot like "Enos."
Thanks to that Latin reference, I was able to find what now seems like an obvious Anglicization in hindsight.
I am descended from Ignace Dajenais / Enos Dashnaw and his second wife Rosalie Lantier, who was also known as Rosella Larkin. Perhaps more on the many forms of "Dagenais" in a later post.