The Bottom Feeders: Moves You Never Use and Why.

[Reynhart]

it would be more efficient to use 2 soul eaters for every 1 Power slash at a higher dmg potency and just ignore Delirium Blade.

No, because the Delirium combo has more potency than the Power Slash combo. (150+250+280 vs 150+220+300)
So, basically, if you have secured your enmity, you use Delirium every time you're not using Dark Arts...unless you really need the few HP that a non-DA SoulEater can give.

[Freyyy]

No, because the Delirium combo has more potency than the Power Slash combo. (150+250+280 vs 150+220+300)
So, basically, if you have secured your enmity, you use Delirium every time you're not using Dark Arts...unless you really need the few HP that a non-DA SoulEater can give.

I'll also add that using Power Slash combo is an incredible DPS loss in two ways : lowest potency combo AND doesn't give the MP that Syphon Strike gives. Power Slash should really only be used if you're in NEED of threat. Other than that, just rotate DA SE and Delirium. Delirium's debuff generally benefits more to the raid than yourself as the MT, and that's why you want to keep it up (on top of it being part of your optimal rotation anyway, since you can't spam DA SE to death). Just look at how MNKs were loved in FCoB just for Dragon Kick, before even talking about their awesome deeps.