From reading around i know where to get the mage essence for JD Sword, but where is the barb essence? All i have left for SOA/WK (not counting some stronghold quests which i may have missed) is irenicus

The location of the Barbarian Half is too obvious to be missed during the game. That's why you haven't found any posts asking about its location. If your protagonist satisifes the class and alignment restrictions (and if you do not cheat during the game), you will find it. There is no need for any more public information about this item's location in the forum.