If you notice real carfully the new enemy, as well as weapons, seem to have small metalic pieces “floating” around a main body. Even the legs or such of the Knights is not fully connected to the body.
The Weapons in Halo 4 show this very easily, you can see it, in your face. Onyx sentinels Have this same design. Small pieces connected to some larger body, probably magnetically.
Also in the concept art even the huge structres seem to share some of this “Floating piece” design. Pretty sick, and nothing we have really seen before.
Which means
1-Enemy design is pretty badass
and/or
2-We may be fighting Onyx Sentinels for the first time.
Vehicles
I hope this means we get at least 2 “Forerunner” vehicles. With the same intresting concept of the new enemy and weapons. May make for some intresting combat.
Like a light “hog/ghost” mix type vehicle, Maybe a Tank/heavy type one and a flying version of something.