Hmm, I'll give that flag a try when I get the chance. I've actually been doing some work on my Autarch. A history of his pieces:
Legs: Dark Eldar Wyche legs
Torso: Eldar Dire Avenger Exarch torso
Head: Eldar Dire Avenger Exarch helmet (though I may change this for an un-helmeted head)
Wings: Dark Eldar Scourge wings (not yet attached)
Pauldrons: Wraithblade shoulders
Left Arm: Dire Avenger Exarch pointing hand with shuriken pistol mounted on wrist. Shuriken pistol clipped off, Forceshield from Wraithblade added in its place
So, a lot of work coming from various sources went into this! Today's story, however, is about the right arm. The new rules for the Eldar Autarch on foot (which this will be, with the Faolchu's Wing relic to be the rules for his wings) has a weapon called the spar-glaive. I originally planned to model this with a Dire Avenger Exarch power glaive arm, but a power glaive is a pretty wimpy weapon compared to a spar-glaive. How can I model the more powerful spar-glaive?
It actually turned out to be pretty easy. I took a ghostsword from an Eldar Wraithblade, cut the blade off of it, and put it in the place of the blade from the Dire Avenger power glaive.

I used these little alligator clip guys to hold it in place while the glue dried. That's a pretty big glaive! Compared to the old power glaive, it's huge:

Here's how the Autarch is looking with the new weapon:


So at this point I consider most of the conversion and modeling work done. I may want to find a way to get his right leg to look more armored, but I might just put a grenade belt there and call it a day. I still need to get a basecoat down on the arms and shoulders, basecoat the helmet (or find an unhelmed head and paint that), another basecoat on the legs, then do all the more detail-oriented painting. Once I'm done painting the model I will attach the (separately painted) wings.