I think the "corruption" is meant in two different senses here. IIRC the story in the Codex has magic warp-blood that corrupt people when it touches them, that the Knights had to protect themselves from. Not corruption in the sense of being seduced away by demonic wiles.

The Draigo fluff is the best. It's not even a character background, it's just a list of the things the guy has punched. That entire GK dex is some clownpants nonsense.