Pelinal's Aptitude is a craftable set available in all armor types. Your Weapon and Spell Damage both become the highest of the two values.
Pelinal's Aptitude is part of the Dark Brotherhood DLC. The crafting station is located in the Gold Coast (Colovian Revolt Forge Yard). You can craft any armor, weapon or jewelry of this set in any motif style you know, as long as you have 9 traits researched (per item). You can trade crafted pieces to other players. Each set item becomes bound on equip.
Found in Gold Coast
ESO
Sets