Hi,i was farming Nahpui Quarter and i had a req9 strength celestial shield gold drop...when i identified it it had -5(19 chance) only...I wanted to put a +28 hp to make it "look" better and i couldnt...I am not sure why...Can someone please tell me?thanks in advance
The Hp mods are the same for an shield but you can only upgrade shields that drop in Nightfall, Hall of Heros and the chest at the end of The Deep / Urgoz.
Shields from anywhere else in Cantha and Tyria can't be upgraded.
If you feel lucky and are patient, hold on to that shield. ANet changed inscriptions on all armors recently, so there's always hope that they might do the same for weapons/shields too someday.