The hook type or whether you can blackmail (or be blackmailed) depends on your faith's masquerade doctrine. If it is strict, asking mortals for permission is a strong hook worthy crime. You certainly would not want your liege to know, unless you are too powerful to oppose.Also, I recently got a friend and VTM veteran into playing the mod. He noticed that sometimes, hooks related to feeding behaviors seem to be strong hooks, which may be a tad too powerful for something that relatively harmless (his example is the consensualist predator type), and that it's odd for vampires to still talk about consuming mortal food and drink during feast events.
Strong hooks via secrets and blackmail are a mere convenience anyway. Bloodbind all your vassals you cannot find an excuse against.