Reported by: Durim
It's possible this is not a bug but that the code simply changed at some point.
My understanding is (without artificer): Level 50 -- 6 points
Level 45-49 -- 4 points
Level 38-44 -- 2 points
I have killed: Valnan (L50) -- 6 points
Viscerant (L50) -- 6 points
Vahdrehl the Faceless (he was in my group prior to the kill and I'm fairly certain I verified this level is 45+) -- 4 points
Aeridon the Warder of the Glade (L45) -- 4 points
Ignis (L50) -- 6 points
That should be 26 points which according to an old source is sufficient for Level 5.
Durim has never died, nor ever put the malform on the ground or anything that would cause exp loss.
I wouldn't make such a fuss about a small point like this but DK life is very hard, these kills are very difficult to come by.