If you can somehow spare the points for it, I think a fusion gun would be better on the autarch than a pistol. Any time you're close enough to shoot the pistol, you're ALSO close enough to shoot the shooting profile of the Laser Lance. Since you have to choose between "fire all non-pistols" and "fire all pistols" it means you won't be firing the fusion pistol much--basically it requires that your Autarch be already in assault at the start of your turn.
The Fusion pistol is a higher Strength and damage output, so I would be firing it instead of the lance, just has the added benefit of getting another shot off when engaged.
Understandable. However, if you shoot the Fusion Pistol, you can't shoot the Lance or your twin Shuriken Catapults. This is actually pretty bad; there are times you'd want to use the Lance + the Catapults instead. Remember, you can either shoot PIstols OR non-PIstols in a shooting phase, not both.
So, how does Fusion Gun compare with Fusion Pistol? Well, the Fusion Gun is about twice as expensive, and not really much more effective than a Fusion pistol at 6" Range. However, with the Fusion Gun, you also get to fire your Laser Lance and your Shuriken Catapults, because it's not a PIstol Weapon. This seems like a big advantage to me, and is really what the extra cost of the Fusion Gun is paying for: the right to shoot your laser lance and catapults alongside it.
What are the advantages of Fusion Pistol? Well, it's cheaper, which is nice. Also, if you are already tied up in assault on your own shooting phase, you can shoot it.
So let's imagine the best case scenario for Fusion Pistol. On the first turn, you shoot your Fusion Pistol then charge. Then, two assault phases pass and it's your second turn, and you can shoot the Fusion Pistol a second time because you're allowed to shoot pistols in assault. So you get 2 Fusion shots, in the absolute best case, over the course of 2 turns. Not bad! In the same circumstances, a Fusion Gun would get only 1 Fusion Gun shot, 1 Laser Lance shot, and 4 Shuriken Catapult shots on Turn 1, and one Shuriken Pistol shot during the second turn. So, we're trading off 1 fusion shot, for 5 Shuriken Shots and a Laser Lance Shot. The Laser Lance is lower strength, yes, but that's a lot of Shuriken Shots. I'd say, it's a tossup at best, even in the best case scenario for Fusion Pistol.
Now let's take a more typical Scenario. You shoot your Fusion PIstol, then charge in with your Shining Spears and either wipe out the enemy in one turn (likely) or finish them off in their own assault phase (possible), or you weaken them and the opposing commander uses Fall Back to get them out of assault so he can put some shooting on your Shining Spears (likely).
I consider all these scenarios far more likely than the one in which your Autarch is still in melee on your own following turn. And in all of these, the Fusion pistol gives no advantage (since you're not in melee during your own shooting phase) except being cheap. You get to fire the Fusion Gun just like the pistol in the following turn. And in fact, once again, the Fusion gun fires along with the Laser Lance and both Shuriken Catapults!
Now granted, being cheap is nice. It's cheaper than the Fusion Gun. The Fusion Pistol has that advantage. And there ARE times you'll be stuck in melee potentially for more than just 1 or 2 Assault Phases, perhaps against a very tough enemy like a Dreadnought or a vehicle that stubbornly refuses to fall back off an objective and must be destroyed. And in these circumstances, the Fusion Pistol may eventually be worthwhile. I happen to think the Fusion Gun is superior due to the way shooting rules work, but there's no reason a Fusion Pistol can't pull it's wait. Just a thought.
You have your troops cost listed as 200, but 20 Defender Guardians cost somewhat less than that. Perhaps they have weapons platforms with them?
You've listed 18 Striking Scorpions as having a cost of 382, but this isn't the correct cost. A standard-wargear Exarch costs the same as a regular scorpion, so your cost should be divisible by 18. 382 is not.
Gah I need to put version control onto my excel file, one at work is out of date 
OK so the point correct list looks like:
Spear Head Detachment +1 CP - 1500 points on the nose.
HQ - 122
Autarch Skyrunner - MandiBlasters, Fusion Pistol, Laser Lance.
Troop - 220
2 x 10 - Guardian Defenders, with AML on HWP, this lets them add to the reaper firepower.
Elites - 362
2 x 9 - Striking Scorpions including Exarch with Biting Blade.
Fast Attack - 261
1 x 6 - Shinning Spears including Exarch with Star Lance.
Heavy - 324
3 x 3 - Dark reapers with Exarch no upgrades.
Flyers - 211
Hemlock.
Pricing looks good to me.
