I don't think the Lich King is a font of necromantic energy, so much as simply tapping the source, an ability that he extended to his servants in some form or another. In that respect, the death knights that break free (PC ones) were granted their abilities without a safeguard put in (a limiter to block retaliation or a means of revoking the tapping ability) and as such, when they break free, still retain the ability to tap the necromantic source (the spirit realm is usually attributed as the source).As for the light, its a revolving current. The beings (both mortal and immortal) who serve the light, grant power to it with their faith. In the same context, the few who serve the light who champion the cause of the light (paladins and priests) are also able to draw upon the power and use it to help their allies or smite their foes. As such, because of this being granted to them, their faith is considerably larger and grant more to the collective than most.At least, that's my theory, based on prior RPG experience and a lack of a divine being.
The thing is that wow is built like a story, events happens, thne other events happens. So basically the Death knight in Epl is always in wotlk beginning. If you look it as a storyboard who devolops then time passes. So no matter how many time a person creates a DK and does the event, it will always be the same time in the story. So the lich king does not aware of that happens just bcs people done the quest before and in the game it ends up 10 000 dk or something who works for the other side(numbers are really out of reality, just making a statement).*spoiler alert*Also as the story progresses in Northrend you become aware of the lich king knows of the event that happend in the Church of light, because He is building a new ebon blade in ice crown. You know this because of quest who leads you there.*spoiler alert off*The TBC story on how Blood elf saps the light out of the naaru, is kinda in the dark until late TBC. You never really understood why the naaru allowed itself to be capture. It could have fled before the invasion. Later it is revealed about Velens vision and you understand it was a part of a prophecy and the naaru did it of free will. It was the only chance it could end the blood elf crave for power and make sure the sunwell never was used to summon a full blown legion invasion. So that the heroes know then and how to stop it in time. Also so that the drenai could get some space from the legion and its allies.But i liked the article it raises some question on the agenda of light and the will of the lich king or unholy energies.
In the char creation description of the blood elves it says they force the light to serve them.
My theory so far:In Warcraft 2, death knights were (as wowwiki says) more of mounted spellcasters. That's basicly a lich on a horse. Now, in Warcraft 3 (and thus WoW), new type of death knights arose. They changed from the (more or less) traditional magi to fighters, drawing their aditional powers from runes.As the lore suggests, rune magic is very old way to use the ley-lines not by study, willpower and traditional ways of mages, but rather by crafting symbols that do the work for you. Because of this, even an amateur (such as a former warrior rised by the lich king) can become a death knight. Why is there such difference between PCs and NPCs? Maybe because the nature of the new (PC) death knights. Strong undead units which were taught the basics of runecrafting. And NPCs? They do it for quite some time. They are experts in the field, so to speak... this is like asking why Rhonin Redhair is more powerfull than any PC mage. Lich King aligned death knights have acces to better learning methods. Lich King himself, certain researchers and let us not forget the vrykul...On the other hand, PCs have three trainers, specialized in rookies. What would you do if a level 80 death knight came to learn last and the most epic spells? "Oh, you're the best you can get... did you try to, like, summon an army of dead? Or something?"What bothers me more is the exact physical nature of the new death knights. Are they even undead? They sure don't seem like the Forsaken - with the obvious exception of Forsaken death knights themselves. Maybe another, more powerful strain of the undead... with more abilities from their life. (Such as the blood elf mana tap.) Or they might not be undead at all. Just normal people which were bonded to the Lich King's will. Which, as we saw in Warcraft 3, is the only reason undead really work for him.So, I wouldn't disagree with the idea of ley-lines manipulation... runes are just a different approach.