An overriding theme behind the greatest terrors that lurk in the Deadlands is that evil is a choice - to become one of the Reckoners' greatest servants, granted a fraction of their wicked power, a person must willingly choose the path of sin and become so steeped in evil that his soul is black with the crimes he has committed against his own kind.
And that's BEFORE she becomes an almost-immortal killing machine that is an avatar of the Reckoners themselves.
Servitors are as varied as the circumstances that create them. Some might look human, such as Darius Hellstromme; others might become changed by the dark powers granted them. A servitor of Famine might be rail-thin or immensely fat; a servitor of Pestilence might be a visibly diseased wretch or someone so beautiful you cannot help but touch her - and catch the host of ills that lurk beneath her skin.
A servitor's abilities relate back to their patron's powers, but always include one thing - near-invulnerability. Servitors are immune to damage except for one key weakness, a key weakness that relates back to their moment of elevation into their current state. For example, a servitor of War whose final act of evil was the slaughter of a Puritan village sitting down to Thanksgiving dinner might only be vulnerable to weapons made from the silverware those villagers were using... or might only be weak on Thanksgiving day... or could have a fatal allergy to turkey and cranberry sauce. Reverend Grimme's weakness is the walking cane he was given in good faith by the very people who killed and ate him, as another example - their good will turned to wickedness is what empowered that cane to strike him. Too bad it washed out to sea after the meal, eh?
Game Information and Marshal Uses
Servitors are rarely one-off, or monster-of-the-week, enemies; each represents a chunk of the Reckoner's power, which is something not granted lightly or to fools. Rather, Servitors are often best used as recurring enemies. Note though, that the Reckoners are capricious, and sometimes the people they granted powers descend into near-bestial states and become little more than wandering engines of destruction.