i think Ball only drops it in the older versions...
in this version the only way is gremory chest and later on FoV you can get it from Mythis (black market) and even the normal lady that selling accsessories she sometimes sell unique.
also the House of Secrets give you unique items...
but well... when you reach FoV - unique weapons and armors are really crap compared to the weapons and armors you can buy from the merchants for around 50k each...
