: And it's
: Soulblighter seems to have favoured Trow as his generals,
: as seen in forest heart. We don't really see much of
: Shiver's army in TFL, but it seems to have been based
: around Soulless, Ghols and lots and lots of Thrall.
: Presumably she had some necromancers and trusted ghol
: chieftains to oversee battles in which she couldn't
: give mental commands to the undead personally.
For the Trow, it's different; the Trow have a direct tie to Balor because HE released, and that's why they helped him: they wouldn't dare break that pact, partially for honor, partially because Balor was ALSO the person who trapped them to begin with. Ghols also are firmer allies than the warlocks, because they are directly allied to ALL the Fallen. (The Trow are directly allied to the boss of the Fallen.) The ghols ALSO hate the dwarves like crazy, and the dwarves side with the light. Finally, the ghols have more or less always been on the side of the dark, and so would obviously ally themselves to the Fallen.
The warlocks, however, are allied only to the Deceiver. They are somewhat similar to him in motivation, and they probably respect him more than anyone else outside of their order. The warlocks also would appear to have no fear of the Fallen, and their true motives are clouded. They would have a high probability of turning on the Fallen if it so suited them. You have to consider the nature of the warlocks.