There is also a charm you could use to bind spirits to your service. It's even Lanka so only 9 XP, but well it has some issues, some practical and some character/moral
Crowned With Fury (•••)
Concentrating her implacable will upon another, the Infernal crushes her target's psyche with a display of her hellish glory. Green flames creep from her eyes and mouth whenever she commands her newly-suborned lackey, forming a blazing crown that burns above her head while she speaks.
System: Spend 2 Essence and roll Charisma + Leadership (difficulty of the target's Willpower). Success transforms the target into the Infernal's obedient servant. The more successes rolled, the longer the target's servitude lasts, as per the chart below:
Result Duration
Botch Subject cannot be targeted by this Charm
for the rest of the story.
Failure Subject cannot be targeted by this Charm
again in the current scene.
1 One hour
2 One day
3 One week
4 One month
5 One year
The target can resist a command from the Infernal for a scene, but doing so causes her body to begin tearing itself apart under the strain of disloyalty, inflicting one unsoakable level of lethal damage. Each level of damage the target suffers to resist this Charm negates one success
on the Infernal's roll, shortening its duration.
Practically you only have one essence so you would have to stand there for a turn while the spirit you are trying to bind presumably tries to kill you, or else it tries to run and you would need some way to follow. There is also the issue that they can resist if they are desperate enough, even to the point of killing themselves doing it
The advantage is also the moral issue, notice that it says the target's will, not the spirit's. Black Court Vampire? You can use it on them fine. Ghoul? Sure knock yourself out. Ghost? As long as it has enough of a mind not to want to self immolate will work fine. It also works fine on regular mortals, otherwise known as that Black Magic Molly just used on her friends and feels guilty over.
You guys remember the part with the Red King in Changes where the crushing will of the mad almost-god could only be resisted by the most strong willed or though the nearness of the Sword of the Cross. That is this charm. Not to say there are no ethical ways to use it, Black court vampires are corpses puppeted by some kind of cosmic wrongness and they make thralls all the time, fine and brute so turn about is fair play and all just be aware this is one of the charms that is likely to raise among the most red flags given your history, but it is there and in your Favored charms if you want it.