You have an interesting list. I think it will make many of your enemies a little frightened when they see all the rending attacks, the damn near invicible falcon and dragons, and the sheer weaponry loaded on the walkers. Here are a few suggestions I have made for changes:
Drop the Farseers doom and spirit stones.
-Doom is 18" range and since he is with your walkers he should be out of range to use it.
Drop 2 to 4 kisses on your Harlies.
-Even with your holofields they're going to take shooting cassualties before getting into assualt.
-You can bet your enemy will be making target priority checks to hit these guys instead of your DA's.
Drop the Fire Dragon Exarch.
-6 melta-gun shots within 6" and 6 melta bomb assualts are suffecient 99% of the time.
-Only take the exarch if they're foot slogging it. (Which I wouldn't suggest)
Drop vectored engines on the Falcon.
-This vehicle is incredibly resilent with just holofields and spirit stones, spend the points else where.
-May as well take two shuricannons, saves points, better AP but you have to give up one shot
Increase and split your Pathfinders into two squads of 5.
-With the points spared you could have two of these units or switch them for something entirely different.
Think about dropping some of the dire avenger exarch abilities.
-I find it difficult to fully take advatage of all these abilites so I don't bother waisting the points.
-Popular methods of having them is ranged with the exarch with two shuricat's and bladestorm or CC with shimmershield and defend.
Maybe change all weapons on the walkers to scatter lasers.
-24 strength 6 shots are good at killing almost anything.
EXAMPLE CHANGES: Farseer
-Guide
2x 10 Harlequins
-Shadowseer, Six Kisses
6 Fire Dragons
Falcon
2x Shuircannon, Spirit Stones, Holofields
2x 5 Pathfinders
10 Dire Avengers
-Exarch: Second Shuricat, Bladestorm
3 War Walkers
-6x Scatter Lasers
TOTAL=1386
This is just a suggestion of a few changes that leaves you 114 points to play
with. Hope this helps you and good luck playing your list.