The dragon-eagle is a large reptilian animal.
It has no feathers or plumage, with the main flying wings being webbed like a bat, with the webbing between the second and third fingers of the wing, which are widely spaced. The wing webbing also attaches to the sides behind the wing and the neck in front of the wing, also like a bat. The first finger, or alula, is free of the wing, and is clawed and used to help climb. The main flying wings are attached to the torso in the same place and manner as in an eagle.
The head, neck, back, and hindlegs are covered in scales like the ones on bird's feet, and the belly and the underside of the neck is covered in wide scales like on the belly of a snake.
Its tail is 2.5m long, and is wide at the base and tapered to the end, like a lizard. It is not used in flight.
It has a pair of forelegs, which attach to the body under the main flying wings. These forelegs have 3 toes, and have an eagle-wing-like structure, but with the proportions and functions of a plantigrade leg and foot. The forelegs are not used for flight, and have no features (like webbing or fins) that would aid flight. All of the toes have claws, and the first toe is opposable, which allows them to grab things with their forefeet.
It has an eagle-like head and neck, but instead of a beak they have a streamlined reptilian snout with lips like a reptile (not well seperated from the jaw), and a set of uniform reptilian teeth that are adapted to tear and eat flesh.
Most of their anatomy and physiology is like an eagle, obviously excluding the other features mentioned.
They are roughly 8m long including the tail, with a 10m wingspan on the main flying wings. They are only around 500kg in weight. Their tissues are uniquely strong, which allows them to move with great speed and power compared to similarly sized creatures. They have 6 forelimbs (2 forelegs, 2 main flying wings, and 2 extra wings), and 2 hindlimbs (the hindlegs).
They are capable of flight, and fly similarly to a bird or pterosaur. They are carnivorous and predatory, and hunt like birds of prey, though using all four feet to grab. Most of their prey is made up of running animals, like horses or antelope. They prefer to hunt in wide-open spaces, like grasslands. They spend most of their free time (or time not hunting) on high, rocky peaks in mountains areas. They are also capable of travelling over long distances.
As mentioned above, they have an extra pair of wings. What would be the best place and form for these extra wings to help it in flight?