Hello,
So obviously we can say Lock is the worst Caster dps, yeah (Besides Ele.. Not gonna bother talking about that spec.)? For the most part, at least, from my personal experience, having a BiS lock I would say even then my damage is not as high as I'd like to see right now.

Fel Armor is basically "Glyph of Shadow", giving 30% spell power equal to your total Spirit, including other things.

That spirit is really useful, however, we have NO spirit on ANY of our gear, why? It makes no sense to me tbh.

Adding the spirit to the Warlock gear would buff Lock by actually quite a lot, without having to overtune or undertune any spell on the class.