Fortify Medium Armor Skill is a Restoration spell in The Elder Scrolls III: Morrowind that temporarily increases the value of medium armor. The skill returns to its original value when the spell ends.
This spell is not available for purchase in Morrowind or expansion packs. Although not intended for use by the Nerevarine, it can be acquired on the PC by using the console:
Player -> AddSpell "fortify medium armor skill"