Hi, Question about neolitic

I see some items neolitic S and A around, i know that this item makes one armor piece rare, but i'm wondering does the neolitic S puts also a S80 or S84 piece of gear rare or is it just for the S armor pieces???

Also i question, is this 100% or like a chance ??

as far i know it only goes on S gear

ull have to wait till god so pretty much everything becomes S grade except vesper and above if u want it on other weap
tho then again im not sure if it works this way :P

its only for weapons.

I thought it was also for armor... But is it by chance or by 100% ??

Only for weapons S and A grade, enchantment will be too after exchange

and 100% ofc, its not a chance thing, its an exchange - give crystal+weapon =- receive rare weapon