Fullmetal89, I'd argue that Dezco makes for a more interesting character right now than Liadrin did before. Largely because her redemption was extremely half-arsed, whereas his short story was very well done.
And to answer your question, restling, Lady Liadrin is the head of the order of Blood Knights, essentially blood elven paladins. In TBC they took their power from a captured naaru M'uru (who turned out to have been doing so willingly) and were predominantly bitter about the Light abandoning them. Post-TBC they still don't need faith to use divine magic, as they draw directly from the Sunwell, but I'm guessing the majority have had a change of heart as we haven't really seen any assholes come out of the order. Liadrin herself turned from (apparently) a soldier to a preacher talking to high elf pilgrims in the Quel'delar quest chain. Hope that answers your question.