Deathkeeper
Background
Second chance
Ever since Tsainu famously 'came back' to life after his death, Channeling energy from the Pull to become the first undead revenant, there have been people seeking the apparent glory of re-killing a revenant.
Some see it as a purely thrill-seeking endeavour, some as a duty, and others still as the ultimate hunt.
These days, thankfully, most reasonable people consider deathkeeping to be murder.
The undead are people, too
The Blink Treaty secured the status of revenants as people with just as many rights as the living, although many countries haven't officially made the act illegal yet.
Fear of the undead from assorted myths and fairytales has resulted in a strong sense of necrophobia in many cultures across the world that, unfortunately, doesn't seem to be fading soon.
Hardier stuff
Living people are fragile.
Many accidents, diseases and all manner of 'natural' causes can kill an otherwise healthy living person. Some people, like the vena, live longer than others, such as the monoduga, but none are immortal.
From the moment a revenant comes back to the world, their soul is linked directly to the Sphere of the Pull. The exact method still isn't well understood, but what is understood is that the only way to permanently kill a revenant is by piercing their brain with nullrock.
This severs their link to the Sphere completely, and is the only wound that a revenant cannot eventually heal from.
As revenants have only been around since the Great War, even Tsainu himself isn't any older than some longer-lived vena, so it's impossible to say for sure whether revenants are truly immortal, or whether they simply have extended lives.
Difficult and expensive
Nullrock is notoriously tricky to get hold of. It's almost impossible to retrieve from the heavily guarded Drake's Scar, and any mined in Yenagun is controlled by the vena who own the mines.
Even if you can afford it, the act itself is difficult for anyone not trained in swordplay or butchering.
Of course, this only makes the title that much more renowned and desirable among certain people.
'THE UNDEAD ARE PEOPLE, TOO' great title use once again :p Quite interesting to see people attempting to accept the undead and consider killing them actual murder.
Well, they're trying, at least - anti-undead sentiments are still pretty strong in most places. Really wanted to play with this idea; revenants will be appearing in a big way in some sort of future story, for sure.