The Armos are former Knights of the Sheika people. As per burial customs of the Sheika, these soldiers spirits are tethered to this world and stay in the service of the Sheika as the Armos Knights. The Ghini that can be seen roaming the Western Hyrule Graveyard are the spirits which occupy the Armos. The Alpha Ghini was a higher ranking Knight, it now patrols the graves. When dispatched, the other Ghini will retreat back the their gravestone tethers.
The Armos Knight stays dormant, it has been for the hundreds of years since the Imprisoning War. Time has no meaning to the Armos Knight. If a body comes in contact with the Armos Knight, the Knight will awaken, the Ghini within stirring to life. The environmental build up that has collected over the hundreds of years shakes off, the cogs within the mechano-stone construct begin to turn and it lives again.
With age some of the mechanisms within the Armos Knights stone body have worn, they do not necessarily attack, but wander about and recklessly run into whatever may be nearby, including Link. Other Armos Knights do not show these same signs of wear, despite being dormant for just as long. These Knights bound to life, amazingly agile for the giant stone hulk they are.
Below is the very rough concept for an Awakened Armos Knight and the three varieties of Dormant Armos Knight.
Awakened Armos Knight
Dormant Armos Knight – Red Rocks Concept
Dormant Armos Knight – Green Stone Mountain Concept
Dormant Armos Knight – Graveyard Concept