---SPOILER---
keep reading at your own peril...
There is another essence-infused skin in Turabi Gate, though it is kind of really painful and time-consuming to get.
Furthermore, the artifact stats do not seem to be static. Here is what I found thus far:
Cloak of the Shadows – Perfected Cloak, Pure Crystal Shard, Purified Essence. (Armor +10%, +2 to Mechanics, +2 to Leadership, +2 to Stealth, +1 to Action Points)
Impervious Cape - Perfected Cloak, Purified Essence, Essence-Infused Skin. (Armor +12%, +5% to hit, +10% Hostile Effect Resistance of Creations)
Flameweaver Greaves – Perfected Greaves, Solidified Flame, Crystalline Fibers. (Armor +12-16%, +2 to Battle Magic, +2 Fire Shaping, +20% to Cold Resistance)
Legs of the Tyrant – Perfected Greaves, Essence-Infused Iron, Blood Poison. (Armor +14%, +8 Vampiric Touch, +3 Melee Weapons)
Gloves of Savagery – Perfected Gauntlets, Essence-Infused Skin, Blood Poison. (Armor +6%, +2 to Strength, +2 to Melee Weapons, +4 to Quick Action, +2 to Strength of Creations)
Shapemaster Boots – Perfected Boots, Deep Focus Orb, Ur-Drakon Skin. (Armor +10 - 16%, +2 to all Shaping Skills, +3 to Creation Damage in Combat OR +10% Hostile Effect Resistance of creations)
Girdle of Succor – Perfected Belt, Unmelting Ice, Ur-Drakon Skin. (Armor +8%, +2 to Blessing Magic, +2 to Healing Craft, +8 to Creation Armor, +4% Hostile Effect Resistance of creations)
Sunstone Belt – Perfected Belt, Unmelting Ice, Deep Focus Orb. (Armor +14%, +10 Energy Preservation, +20% Energy Resistance, +20% Fire Resistance)