Mixed lists are very difficult to balance in a 1000 point game, but if you want to field one, I feel you are going to have to field the Striking Scorpions on foot as assault protection for the Guardians, unless you know that you will only face gun line armies.
Guardian squads also work much better when fielded in pairs in my experience, and if you give them a Scatter Laser. The Shuriken Cannon doesn't have a long enough range for Guardians on foot, and forces them to walk into range of rapid fire weapons to be able to fire, which is not a good idea in the early stages of the game (i.e. before you have had a chance to thin the numbers of such models), as Guardians are very vulnerable to basic weaponry.
The Dire Avengers look good on the whole, but I think would be better that eight if you can find the points, and the Dual Avenger Catapults would be a substantial improvement over the Diresword.
The second Wave Serpent would need another unit to fill it if you field the Striking Scorpions on foot. Storm Guardians with Flamers and a Warlock with Destructor would be one option, Fire Dragons another.
Wraithlords only threaten tanks with AV12 or more when equipped with an EML and Brightlance in my experience, so if you cannot afford, or do not want to field the Wraithlords with this configuration, I suggest dropping both of them, and finding other anti-tank options, such as the Fire Dragons, although the Wraithlords would help to draw fire away from your other ground units to a certain extent in my experience.
The Farseer may also be better off taking Doom than Fortune, as both the Dire Avengers and Striking Scorpions really do benefit a lot from the effects of this power in my experience.
Overall, the edited list seems to be heading in the right direction, but I feel you need a better balance between the infantry and mechanised elements.
I hope that helps.