Firo is correct:

I was once beautiful in a former life: Bouquets are a lovely arraingment of flowers
But now all that has gone: Withered, hence not vibrant
I sit alone, hidden from most eyes: In Baaj Temple, yet 99% of prople dont visit there
High above, and found only by those who look hard:On second floor of the area Tidus first goes, and on the wall so you have to look for it

As Firo requested, someone may create the riddle