Okay, so the Knights of the Ebon Blade can look forward to being raised as ghouls to serve alongside the survivors, then. Lurid isn’t as strong as Thassarian, and he’s not independent in the same way a death knight is. I suppose that technically makes them “immortal”, but I was thinking of the comparison to demon hunters who can just hop back into their body if they have an immortal demon soul.
From Dark Mirror, an official short story:
Nathanos’ shiny new model in Legion was courtesy of Sylvanas using one of her Val’kyr to make him more similar to a death knight in terms of sturdiness and lack of decay, using some of the same ritual magic. Now, I don’t know of any source on how difficult it is to raise a death knight a second time if their already-made-sturdier body is mostly intact, but the implication is that making new ones from fresh corpses is a rather taxing process, and the Lich King was a very useful battery for this purpose. That’s why the Forsaken couldn’t raise death knights on their own; they had knowledge of the procedure through the Val’kyr, but not the resources required. I suppose it’s possible that the Ebon Blade might have their own power source to fuel such rituals, but if so, it’s rather odd that they a) weren’t raising new death knights on their own and b) weren’t attacked by Sylvanas in an attempt to steal such power. Sylvanas was strangely content to leave the Ebon Blade alone (aside from everything with Koltira), considering that they represented a potential rival to her power.
I just put this up to Bolvar being his usual dramatic self, but it was also true while the Helm was intact, and at the time no one involved considered the possibility of the Helm ever being destroyed. If you have the power to wield control over life and death, then death has no power over you…unless you lose your own source of power, that is.