I'm not sure whether this is a bug or the way it's intended, so I'll just go ahead and post it.
When moving, the Atreus system extends vision around your Templar by one square, from 4 to 5. But after the first enemy phase, the fog-of-war is updated for the whole map and then the vision range is always 6, not receiving a bonus from the Atreus system.
How are Templars like snails? Both move slowly and leave a trail of ichor behind wherever they go.
How are Templars different from snails? Ask one and find out...