Nethercleft Leg Armor

Nethercleft Leg Armor is an armor kit which permanently applies +40 stamina and +12 agility modifications to leg armor, in the same virtual "slot" as an enchantment.

As of Patch 3.1.0 the benefits of this enhancement do not become active until level 60, thus effectively nerfing it for Twinks below that level. Although the enchantment is not removed from your existing item, you will not receive the benefit of this enhancement unless you meet the new level requirements. Thus the new in-game tool tip now shows " Enchantment Requires Level 60 " in red font (indicating the enhancement is not active) if your character is below the required level.

Source
Nethercleft Leg Armor is crafted by leatherworkers with a skill level of 365 who have obtained Exalted reputation with Cenarion Expedition. The components are:

is sold by in the Cenarion Refuge in Zangarmarsh for. You must be exalted with the Cenarion Expedition to purchase this pattern.