Jokes aside, the question of how the Games Workshop Autarchs are equipped is an interesting one. I got both because I wanted to mix and match a bit (as you can tell from my options-obsessed solution here). Fusion gun for one guy, Reaper Launcher for the second, exchangeable back-mounted gear for the rest. I gave some thought to the question of "What if I want the Autarch with Mandiblasters to have the Fusion Gun and I want the Autarch with the Banshee Mask to have the Reaper Launcher?"
And then I decided life's too short.
Notice I built Biff's left arm from a Dire Avenger Exarch's arm (using the one with the Deflector Shield and the pointing finger from the wrist-mounted Shuriken Catapult). The swords that come with the models are too pokey-outy. In other words, I wanted them to take up a bit less space. I'll put a sword on Biff's belt, so no problem there (why have a Banshee Mask if you're not gonna hit someone with a sword?), but I haven't made up my mind yet as to what he should be holding in it. I have an idea, though...