It will come as no surprise to even the youngest scion of la famiglia, that there are many different kinds of incorporeal undead. One should be careful not to rely overmuch on categorization; more than one venerable scholar has met their demise by allowing themselves to be surprised by the capabilities of a wraith previously thought to be harmless.
Even so, it is useful to agree on basic terminology. When we use the word ''spectre'' it is to give a general impression of the disposition and capabilties of a particular wraith. No two such beings are going to be exactly alike, but this primer should allow you to make basic preparations when you're told to sway a specter to our benign guidance.
Origin
Simply put, spectres are wraiths with a grudge and the wherewithal to do something about it. That grudge is most often a deeply personal one, such as the specter's own murder. A wraith who has come into being in this way is, in some sense, a ticking time-bomb. If left to their own devices long enough, there is a very good chance they evolve into a malevolent spectre. Surely a deeply ironic word to use for the dead, but there it is.
Whether such an evolution completes itself in a handful of years or will take centuries depends on too many factors to go into here. Suffice it to say that both circumstance and the force of personality of the wraith in question matter a great deal.
Abilities
The numina utilized by spectres are greatly varied, but without fail the means by which they influence the living world are tuned towards causing harm. Many show no interest or ability in regards to communication, at least not at their own initiative. Unless one considers the hurled contents of a block of knives to be a message. I will name a few commonly seen numina, but this is by no means an exhaustive list. I advise you study known stories caused by the spectre in question, or send a catspaw or two in front of you. Some things are best observed from a distance.
Harrow
This is a dangerous skill. It allows a wraith to influence emotion, turning a group of individuals towards strife and infighting. At best, it causes a lot of distraction. At worst, a spectre can follow up with other numina, violently knocking down a situation that it has set up.
Mechanical Possession
Of the host of numina that allow wraiths to interact with technological objects, this is the most directly dangerous one. If the spectre's haunt includes dangerous machinery, be wary of the odds that it possesses this numina. Whatever else you do, don't get into a car. Or a combine harvester, etc.
Telekinesis
The ability to move objects, with a variable degree of force. While hurled objects can be harmful, they are often not too dangerous to deal with for one of la famiglia. Do ware the specter who is able to utilize their environment to full effect, and for heaven's sake douse any flames you come across. A candle knocked into the curtains is an unpleasant complication, especially when the doors are then held shut.
Wail
A dangerous skill. Though often immediately giving away their location, a specter that can cause this kind of ear-splitting wail is sometimes known as a banshee. They are rare, and fortunately so. Most often this numina is coma-inducing, or even lethal to any human that hears it. We are a bit more resilient, but not that much more so. No, earplugs will not help you. Act fast, or choose the better part of valor.
Means of control
The means of control for a spectre are similar to that of any wraith. They value their continued existence, and are often more aware of what awaits them below than a typical phantasm or phantom. That awareness is a double-edged sword however, as their increased cognizance also makes them harder to deceive or manipulate. Their innate malevolence also makes them more resistant to intimidation, and prone to take risks to harm you, even at their own detriment.
If you are far enough along the path to harm them directly, do so often. Be very clear with them that only their obedience protects them from a one-way trip to the great below. Even so, keep your instructions without ambivalence. Never let your guard down. Even spectres who haved served for centuries have been known to attempt betrayal.
It can be difficult to find and control every single fetter a spectre possesses. Some can even create new fetters, an ability that they will take great pains to keep hidden from you. Certainly, attempt to control their fetters, as they are what ties them to the living world. But do not be lazy and rely on that as the sole means to keep them under your control, unless you are very sure of yourself. Have you heard the story of sloppy uncle Alfredo? No? Ask around.
Utilization
For obvious reasons, spectres make excellent guardians. They love expending their pent-up aggression on intruders. Don't expect to interrogate said intruders afterwards. They are equally useful to secure assets. Simply hide a fetter somewhere that gives them access and give them time to go to work. There's no better way to clear a building and lower property values. Do try to be somewhat circumspect, overuse of this method will attract unwanted attention.
They make poor messengers, and unreliable assassins. They can only operate outside of their fetters for short amounts of time, and targeting a specific individual is difficult for most. The ones that are able to do so however, are extremely valuable. To keep in mind that this makes them equally dangerous to you.