Darth Zangetsu
Super Freak
I think it's purposefully not being revealed yet. The wife might come back and help the main duo. Or she may be around only in spirit and guide Crane through visions so she can finally rest or move on.
I really don't like that they defeat the monsters so quickly though.
i think at some point they are going to fail to stop a monster, and the forces of darkness will have a new soldier. Eventually even from a story standpoint, and to add drama, they will have to fail at stopping one of them.