Hi.
Yesterday i upped my arrets face. It has 6%LL and 187% enhanced defense. Before upgrade it had 347 defense, but after the upgrade it has 341 defense?!
The requirements for the helm has sky rocketet whitch was expected. It now need 196 str and you need to be lvl 72 to wear it.
But how come it didint get upped in the defense?
An Arreat’s Face is a Slayer Guard with a defense range of 93-120.
If you upgrade the item to an Elite version (Guardian Crown), the defense range
will be 117-168. That means that the defense ranges of old and new item might overlap, like in your case. It seems you rolled about the lowest possible defense on the upgraded item, where as the original helmet must have had a pretty maxed defense.
Not a bug. Armors have a varying defense roll. A normal Arreats is a “Slayer Guard” which rolls 93-120 defense. The upped version is a “Guardian Crown” with a defense roll range of 117-168. You simply rolled high on defense on the non-upped version… then the upped version has its own defense roll,on which you rolled really poorly.
Oh god 
Well thanks for the reply. Pretty sad to be honest xD