The Crystal Throne is both the generic name for Seanchan policy and government (TGH, Ch. 34; TSR, Ch. 1) and an actual throne, that of the Seanchan Empress. It is in fact a huge ter'angreal that causes anyone who approaches it to feel immense awe and wonder and as such, is no doubt in part responsible for the great loyalty many Seanchan feel to the Empress, at least amongst those who have been before it (TWoRJTWoT, Ch. 17).
"Few easily shook off the awe they felt, kneeling before the Crystal Throne, with the thirst to obey drying their tongues" (The Path of Daggers, Chapter 24)