So I gave this guy another go today just to see if there was some potential that I missed. I'd originally thought of doing a AotS/Pal split. Unfortunately, You can't be a paladin with AotS because Paladin requires Good alignment and AotS forbids good. If the pact was something different it's a set up that I could see working with the wonky Blast/Pact dice feats. A possibility would be to remove the "not good" restriction from the fiend pact for this Archetype only. I'm not saying that it's an optimal set up due to lack of Arcane spell failure removal in heavier armor, so you're still not that bulky even if you got the save bonuses from paladin. But it would at least open up some of the bulkier options.
Sadly, at this point this Archetype just doesn't have a home in DDO right now. Even if the fear "SLA's" worked, I'm not convinced it would matter. As has been pointed out, most bosses and important targets are immune to fear effects meaning your double Pact damage will not apply when you need it the most.
The latest I tried was as a Chain Blaster: TS Capped, taint the blood and no worse fate (for the shaken on hit) from SE, and up to Drink their fear in AotS. Used the Scare spell and symbol of fear manually cast. It's not as god awful bad as relying on the broken sla's in this tree, but having things run in fear is definitely a pain more than an asset. You can evard's them to help lock them down so they dont run away, but that just adds another layer of clunk to the playstyle. Not to mention Symbol of fear has a slow cast time, and Scare has a really big delay between time of cast and when it goes off. Also, shaken doesn't seem to proc the double pact dice even though it is a form of fear. It does when things are feared by Scare tho. If it would work with shaken, as it seems like it's intended to, then the synergy between AotS and Soul Eater would be great for the fortitude cut on hit and the shaken on hit causing your pact dice to double. I still agree that being as this is all about fire that the swing should have went heavier to pact dice than to base dice in the feats but that's a minor issue compared to the other major issues this tree has.
The Beam shape just needs scrapped. If it was me, I'd do something like this:
Eldrich Blast Shape: Projected Fear- Transforms your Eldrich Blast into a blast of fiery terror at a distance damaging all enemies in a small area around your target. Enemies hit by this shape become shaken in fear. -10/15/20/or some other negotiable number% Eldrich Blast attack speed.
This way you're not penalizing the Pact damage that this tree is about, providing some decent AoE options of Warlocks, but still having a drawback of being slower. This would make Projected fear the slower but harder hitting Eldrich Blast shape, self synergize with the Drink their Fear point once it works with Shaken effects, and offer an true AoE form for Warlocks.