I've studied the Eye for something like half my life. We know what it does. Its a defensive weapon of incredible power.
We know how the magical crystals fit into the sconces. They glow brightly when properly slotted.
What we don't know is how it works. Scholars from far and wide have come to our town, examined the magical interlacing, and gone away shaking their heads. Where does the device store its energy? How does it focus that beam? What coalesces the fire?
Truly the ancients were head and shoulders above the abilities of modern sages.