1.2 Unique shield without quality enchantment option

[pstone]

The unique small shield "shimmer scale", found in the Cavern of Xaur Tuk-Tuk, cannot be enchanted with the usual quality improving enchantements (like fine, exceptional etc). I think this is an oversight or bug, all other unique items allow this improvement line (and it makes the shield quite useless, despite its other nice enchantment options).