The Planar Edge

The Planar Edge is a main-hand specialty axe made by Master Axesmiths who are the only ones who can wield it. It gives a bonus to critical strike rating and attack power.

Source
This item is crafted by Blacksmiths with a skill level of 350 who also have the Axesmith specialty.

The plans are taught by the Master Weaponsmiths in various cities.