But Merlinus doesn't follow conventional Fire Emblem rules.
1. He doesn't die. How many other units in Fire Emblem (from 1 to 9 and FEDS) come back in the next map, even if they die? FE10 is a different case because it's story line based (fighting your own units).
2. He doesn't level up by gaining Exp. He just levels up once a map. How many other units in Fire Emblem do that? Here's a hint. It's starts with a Z and rhymes with Nero.
3. He has no commands other than Wait. How many other units do that?
If I see good logic for why Merlinus should be considered a proper unit, I'll back it. But right now, all I'm seeing is "Convey has a face, a name and certain stats. Therefore, he's a unit". And I'm not buying that logic because stats don't make a unit. Commands do. Last I checked, we rank units on how well they utilized their commands (I feel a giant Nino shitstorm coming again), not for how well they exist.