I rather like the idea of Edgar as the Ranger. It seems to make a great deal of sense, as well as bringing strength to an otherwise weak character.
Point one: In the beginning of the first episode, Titania and Oberon let slip that there is something not quite right about Edgar and his relationship to them. In episode two/three, he also mentions that his appearance as a human is unusual for fairies - and this trait doesn't seem to be from either of his parents. What this means is, for now, purely speculation, but the writers made a point of not once, but twice, pointing out that there's something unusual about Edgar.
Point two: Edgar has indeed traveled with his identity hidden by a cloak - in KQ7. The cloaks are remarkably similar, and the fact that they both obscure his identity is important. As was previously mentioned, the reasons that the Ranger's identity is hidden are twofold: one because Graham and other characters would recognize him, which he does not want, and two because the player would recognize him, which the designers do not want. His motivation for moving unseen is unclear, but he has done so before, and has the magical abilities to do what the Ranger has done.
Point three: Edgar's apparent inaction is suspicious - especially compared to his previous willingness to go against powerful sorceresses to help Rosella. His actions were important to the defeat of both Lolotte and Malicia. His fatigue would also make a great deal more sense if he were, in fact, moving clandestinely at night.
Point four: Edgar's entire character is based on hidden identity, being more than he seems, and proving his strength (if at times ineffective) despite his appearance. In KQ4, his introduction as the ghoulish son of Lolotte belies his true nature, just as much as his transformation by Malicia into the Troll King in KQ7. It would be quite fitting if his finale also carried this theme.
So, though it may be a long shot, I'll be placing my bets on Edgar. After all, it's the quiet and the meek that surprise us the most.
