Ok, I felt summoned to this thread; did someone invoke the name of KaneSolo?!?!?!
Just kidding.
From the games I’ve played in, any creature with a special ability is able to use that special ability without issue, i.e. endurance cost, health cost, etc… unless the entry specifically states it.
So an undead using something like a life drain touch (melee) attack is able to do that as many times as the entry says it can, but does not spend any Endurance.
It’s kind of like the spiritual entities in the back section of Encountered, who have something like healing abilities, but do not spend Endurance to heal… it is innate.
So let’s examine the aforementioned “Kullsarin”:
Let’s first keep in mind that Kullsarin is Lord of the Undead, and a threat level 10 creature. Those are some seriously bad creatures once you get past level 6.
His Aura of Fear, Density Shift and and Nihilistic Touch are at will, not subject to recharge, so he can use them every segment if he chooses (keeping in mind, he still has to split his dice pools to touch any party members over multiple segments).
His Wave of Agony, however, is a limited use ability with 1 charge, and then taking an hour before it recharges. So that is a one shot attack for any battle.
So, basically, in the spirit of running a campaign where the party will encounter and contront Kullsarin, they better be REALLY prepared. But in the general running of the game, special abilities are just that, special. In the case where an undead lists some Wielding sources and intentions, **I** would assume they are there to support the existense of the specials, without giving them full access to wielding (unless they have an Endurance pool).
You can also look at it like this: this being used to be a serious wielder, until he became undead. It does not mean he lost all that knowledge, just the ability to access it for now…. unless he feasts on the souls of the party to give him temp Endurance ... MUAHAAHAAHAAHAA