Two Armies is the first book in the Sky Highway Saga, by Andy Wright. It takes place in the Emergence Era of the Lower Knight timeline. It was self-published on Lulu.com in 2006, but is currently not available for purchase.
Two Armies begins immediately after the closing events of Seeds of Doubt. John "Nat" Nataka travels with two friends, incognito, to the Sky Highway.
Nat is quickly separated from his friends and captured by a special forces unit which conscripts him into their army.
Nat's armor is taken away and he is forced to go through the entirety of the army's training. Being lost in a world that's still entirely cut off from his homeland intensifies the situation.
While this is happening, Nat is being followed and watched by a Shaynokeiz being, a Grandmaster Mage Rakh Knakh. Rakh is an extremely powerful immortal, his body's normal state being that of sentient smoke which is able to transform into multiple shapes and possess any human's body after killing it. Nat's emergence on the Highway is seen as significant by those for him and against him, motivating the Three Corps to manipulate his introduction in subtle ways.
Rakh Knahk finally confronts Nat while he is on duty during an occupation of a small Natoas village in the Southern Hemisphere. The one oddity of the town is a strange metal band surrounding the one Element in the village. Sealed in the band is a platinum sphere, similar to one that would attach to Lower Knight armor. The locals call it the Namasokai sphere, and claim it's part of the Natoas' most important prophecy.
To protect the villiage, Nat fights Rakh Knakh using a special sword a local swordsmith makes for him.
The fight leads to Nat's armor, which had been locked away, to break itself out and return to him. As it arrives at the scene of the figtht, it merges with the Namasokai sphere in the band around the Element and transforms somewhat. Reunited with his armor, Nat is able to defeat Rakh Knakh, who escapes destruction by turning himself into a crow and flying away.
The Sky Highway is an orbital network of city-sized space stations called Nodes. They're linked together by cables called Bridgeways, that allow vehicles and trains to travel quickly and easily between them. The nodes are suspended 500 kilometers above the surface and mimic geosyncronous orbit via a special arrangement of tethers, tens of thousands of kilometers long, and huge countermasses.
Arriving in this strange world of isolated but interconnected regions, Nat is thrust into the boil of international politics in a world he knows nothing about. That world also knows nothing about him, a Lower Knight from a region where Lower Knights are respected and feared. In the rest of Atanoah, Lower Knights are greatly disliked and most are undisciplined.
The Sky Highway is also full of technology far more advanced than anything in Two Edged. Weapons, vehicles, infrastructure and energy systems are all centuries ahead. The two biggest exceptions are in computing processing and encryption power and in technology/duedamus hybrid systems.