First of all, I should point out that I don't like making sweeping changes to an army list generally. I usually go about slowly evolving the force through little changes into something that I'm happy with. This means that by the time that I get to my final build, I've played quite a few games with the army in a similar form and know what it reasonably can and can't do. I feel this approach works best for me, it may not though for others.
Enough waffling on, onto the list.
Autarch Rosu - Power Weapon, Fusion Gun, Mandiblasters
10x Dire Avengers - Exarch with Bladestorm, Shuriken Pistol and Diresword
Wave Serpent - Vectored Engines, Scatter Lasers
5x Guardian Jetbikes - Shuriken Cannon, Warlock with Embolden
12x Storm Guardians - Flamer, Warlock with Enhance
Wave Serpent - Vectored Engines, Missile Launchers
5x Fire Dragons
8x Warp Spiders
Wraithlord - Brightlance, Wraithsword
3x War Walkers with double Scatter Lasers
Falcon - Vectored Engines, Holofield, Starcannon
Total - 1747
Here's my suggested rebuild:
Autarch Rosu - Power Weapon, Fusion Gun, Mandiblasters - 100
I prefer to run a Farseer instead of an Autarch. I find the way that a Farseer acts as a force multiplier to be very handy, but if you want to run an Autarch, this is a reasonable way to do it.
10x Dire Avengers - Exarch with Bladestorm, Power Weapon and Shimmershield - 162
The Diresword is one of these really cool but utterly useless weapons, the odds of one instant killing it's target is appalling. Much better to spend the points on making the squad more survivable. Twin Shuriken Catapults is another perfectly acceptable option for the Exarch when in a Wave Serpent.
Wave Serpent - Spirit Stones, Bright Lances - 145
Vectored Engines are a want, Spirit Stones are a must have. If your tank can't move, than any enemy can hit it automatically in HtH and bypass the energy field. Don't let this happen. The Bright Lances will help you deal with heavy armour more easily from afar.
5x Guardian Jetbikes - 105
Cheap scoring unit that is reasonably tough and very mobile. Keep them in reserve so that they're more likely to be alive at the end of the game. Killing things should be secondary to them staying alive to hold or contest objectives. They're small enough that they will generally only have to take one leadership test most games so I don't bother with the Warlock.
5x Rangers - 95
As above. Don't be afraid to go to ground with them if you have to, to keep them alive to hold that objective.
11x Storm Guardians - 2x Flamers, Warlock with Destructor - 127
Enhance looks nice on paper, I5 and WS4. But in the real world, Guardians just don't wound often enough to make it worth it. Better to kill more before hitting combat so less of the enemy get to hit back. The triple flamer layout of this unit should also help with orks and guard blob squads, especially after you tank shock into the edge of the unit to bunch them up. Keep a spot free so that the Autarch can jump in if his transport finds itself burning.
Wave Serpent - Spirit Stones, Bright Lances - 145
Don't rely on only one brightlance, always have two in case the first one goes down.
6x Fire Dragons -96
These guys don't need any explanations really. Where possible, have the brightlances pop landraiders and use these guys on the termies inside.
8x Warp Spiders - Exarch with two spinnerets, powerblades and withdraw - 260
Use this unit to either finish off weakened units or shoot then assault large units like guants or guard blob squads. Their 3+ save should keep them safe long enough for them to use withdraw at the end of the opponent's turn, to allow the rest of your army to shoot them.
3x War Walkers with double Eldar Missile Launchers - 210
30 points more than the original unit and much more likely to blow up tanks. Still excellent vs infantry when they switch over to plasma missiles instead of kraks.
Wraithlord - Eldar Missile Launcher, Wraithsword - 125
The EML is 15 points cheaper than the brightlance on a Wraithlord. Better to put BL's elsewhere.
Falcon - Spirit Stones, Holofield, Eldar Missile Launcher - 180
Move up to 6" and fire three S8 shots, or move 12" and shoot at infantry.
Total - 1750
I had about 50 points left over at the end so added in the Exarch for the Warp Spiders and the extra Fire Dragon. You could easily use those points to take a Farseer instead of the Autarch, or simply increase the size of your Ranger and Jetbike squads. Try things out and see how you go.
As you can see, I haven't changed what units "Autarch Rosu" has taken, just tweaked them slightly into something more cohesive. The army now has plenty of high strength weaponry to deal with hordes and all of those EML's will be just as effective vs hordes like guants, guard and orks. The list is fairly mobile with all units moving at least 6" a turn and still firing at full effect (except the rangers which should be placed as far from the action as possible in kill point games, and preferably holding an objective on top of a ruin in objective games.
Hope you like it, enjoy.