On the topic of Wights, this is how they are raised according to Page 120 of Night's Dark Masters, the Spell of Awakening:
"As re-animate, but you create Wights instead. The remains used must be those of a Character with an advanced career"
In the RPG, your "career" refers to your class. It's your job/vocation, it determines your specialties, your progression, your abilities, your skills etc. etc. There are Basic Careers and Advanced Careers, and in order to enter an Advanced Career you need to complete a Basic Career corresponding to the Advanced Career in question. All Basic Careers give you an option to which Advanced Career you want to advance to. The gist of it is that Wights can only be Characters with Advanced abilities, and not just some no name. Interestingly, this description says nothing about martial ability, which is probably just an abstraction. You could theoretically make a Guildmaster with no combat ability into a Wight.
This is the description of Wights from page 127 of the same book:
Here is necromancy at its peak—a creature with the dark will of the Spectre combined with the bodily strength and unflagging discipline of the Skeleton. Though their flesh may rot, their bones remain strong, and their minds retain their mastery of the art of combat and their lust for slaughter. As the Skeleton is to the Empire's foot soldiers, the Wight is to its great generals and heroes.
However, the creation of a Wight requires the deepest study of the black art. As such, it is typically only done for those whose mortal existences marked them as worthy of such immortality. Vampire lords may occasionally bestow the gift on close friends or family, but in the main, the honour goes to their greatest warriors and generals, so they may continue their martial careers in death. There are also Wights that come to life through some magical accident or ancient curse. The races that lived in the Old World before the coming of Humans buried their dead in barrows entwined with ancient magic. Their Skeletons have been known to rise up to defend their resting grounds or respond to a summons from a powerful Vampire.
Regardless of their origin, they are skilled in the ways of war, and all have an eternal thirst for battle and warfare. Most carry terrifying Wight Blades that cut through armour like the cold talons of a Spectre, and many are mounted on hideous skeletal Nightmares. The image of the Wight riding into battle with lance and sword is so common that, amongst the Vampire armies, Wights are often known as "Black Knights."
Their personalities are not as complete as that of a Vampire, but their intelligence is deep and their goals often extensive. Wight lords are sometimes found ruling small duchies or necropolises or harnessing armies of Skeletons, just as their Vampire masters do. They also lack the great charisma and noble bearing of the Vampires, but since Wights have little taste for political machinations anyway, they are quite happy to leave such things to their masters. Like any good warrior, the Wight knows his station and seldom exceeds it.
Most of this information is interesting but not really relevant here. Here, the implication seems to be that you can turn anyone into a Wight, it's just usually reserved for those who are worth it, but I prefer the idea that Wights can only be formed from those who are capable of withstanding the process.
I agree that you probably can't just take any dead volunteer to use for this purpose, but it seems more likely to me that the stopping point is that it's much easier to immortalise a great Khan into a spirit capable of doing things than it is for Joe Bloggs. But Niedzwenka's spirits would then sidestep this problem by already being such... beings.
That is probably the case. But then you run into another problem, and that is the fact that strong spirits are rare. They require a specific environment that nurtures them and allows them to exist without being corrupted, and they also tend to be extremely localised. One could argue that it's more likely for us to gather "worthy humans" than it is to collect spirits capable of performing these tasks.
Obviously, we're operating on complete speculation since we don't know how much theoretical strength is needed. Can a Spite handle a tributary? I feel like if that was the case the Grey Lords would have attempted it. It's certainly more efficient than Lornalim, which requires a deposit of silver and/or gold.
I'm not too optimistic about spirits picking up the slack, but we'll see how it turns out. Niedzwenka is certainly one of the best options for that field at least.