Try amazon basin.
Armors :
https://www.theamazonbasin.com/wiki/index.php/ArmoNotice the difference between, for example with Sigon's shield :
QLvl = 22 (as any Tower shield)
Lvl = 9 (special setting for any set/unique item in the game)
rLvl = 6 (required level to equip it)
To have a chance of spawning it, the item level must be at least equal to the highest between QLvl 22 and Lvl 9.