The Eye of Ashur is a powerful artefact that was created by Ashur, a mighty something (the Tales that came from that time are delivered in a way where it's hard to pin down if someone was a warrior or a wizard). According to legend, he formed it from his own eye after losing it in battle. What is not often mentioned in the legends is that it was his other eye. For some reason the artefact is specifically designed to combat red dragons.
It was later used to slay the red dragon Lord Arkathrax in the Freeborn Rebellion. What happened to the Eye after that and how it came into the possesion of Lady Myulana is currently not known. After the Eye assisted in killing Lord Arkathrax, its power was somehow diminished and Lady Myulana wanted to recharge it in some fashion, using the volcanic Leylines under Polaron, possibly in a place where it was originally created.
Draven thought about creating a copy but he would have found someone (or something) that was mightier than him to use the eye. Even if he would have been able to do so, it would still have been dubious if he could fool Lady Myulana.
The Eye also was inhibited with organized astral energy unlike the Astral plague, what gave Draven some ideas to fight that disease.
When Lady Myulana first acquired the Eye, it was in a weakened state (see above), but
+4 Constitution +2 Resist to all Saves +Bane red Dragons (instead of a simply Bane dragons but just on natural weapons.) If you cast a Level 1 spell you can cast an additional Level 1 spell on the same target as a free action. If you want to do that again on the same day it will cost the caster: 3HP, for every additional use it will cost 3HP more, so for the third use of that ability 6 HP, then 9HP... And so forth.
Fire resistance (?) What I think is really strange, because the number or if it grants immunity should be known from an Identify spell, there must be a special case for that, perhaps just Fire resistance against red dragon breath or something. +4 Constitution +2 Resist to all Saves +2xBane red Dragons (but just on natural weapons) If you cast a Level 1 spell you can cast an additional Level 1 spell on the same target as a free action. If you want to do that again on the same day it will cost the caster: 3HP, for every additional use it will cost 3HP more, so for the third use of that ability 6 HP, then 9HP... And so forth. And 1x per Day you could do the same as above but with a Level 2 spell.
To create a copy of the amulet Morduval's eye might have worked but it might have been a bit too big.