20x Daemonette's of Slaanesh - Instrument of Chaos, Alluress
10x Pink Horrors of Tzeentch - Iridescent Horror, Instrument of Chaos
Like Nicanthrope says, 11 Horrors for the extra warp charge would probably be better. An in the same vein, I'd probably drop the Instrument from the Daemonettes in favor of a Lesser Reward on the Alluress, for an Etherblade. Perhaps even 1 Daemonette to boot, to make that a Greater Etherblade--I think you'll see better results with S4 than S2, for all that it's WS5, I5, master-crafted and AP2; that's the main point of failure there.
Possibly drop another daemonette to give the Herald of Khorne a lesser etherblade to boot. He already has decent strength and furious charge, so giving him AP2 rather than AP-, plus a master-crafting, will boost his damage output considerably.
Hmm, not much in terms of anti-tank, though I dunno how many tanks you'll run into at 500. You could probably wreck transports with the hounds and herald, if need be, I suppose...
As the league grows to 750-ish points, or whatever the next jump up is, I'd consider getting some more hounds and then some Screamers--their anti-tank capabilities are pretty damn cool.
1500 feels like the least number of points I'd want to field Fateweaver in, for all that I love him to death, since he costs soooooo many points for having A1 at WS1 and I2.