The Avatar isn't a DE Avatar or a CWE Avatar. He is THE Avatar. He is born from your deepest fears, your deepest doubts, and has returned to destroy in the name of the 'Greater Good' of the Eldar race.
Neither is he terrifying or inspirational. If anything, he inspires and imbues those around him with a portion of his prowess. Couldn't think of any way to describe that.
The 6(7) was another blooper - he's 7 on the turn that he rises out of his Vessel (this is alongside having a 2+ Invulnerable Save as well!) but reverts to 6 in all turns onwards. I'm glad you like the Melta CCW though - who doesn't like having 7+3d6 for Armour Penetration?