Board Thread:Warhammer 40k General Discussion/@comment-69.142.168.238-20140724005240/@comment-1653258-20180805162120

Horus was more than a son to the Emperor. Horus was the best friend he ever had, the best friend he ever will have. Horus was his favorite person in the whole Galaxy. He was the Emperor's pride and joy. As some onf you have correctly mentioned, the Emperor, who is still a flawed human being, albeit a lot less flawed than any other human being in history, couldn't bring himself to believe his pride and joy did what he really did. He saw Horus as someone who was sick, not someone who was wilfully evil.

I would say there would be a relatively small chance Horus could have beaten the Emperor, even if they were going all out. Horus managed to mortally wound the Emperor. I would assume the Emperor would have made some attempt to defend himself, rather than just stand there and let Horus kill him. If Horus was powerful enough to mortally wound the God Emperor, then logically it would follow that it is possible for him to beat the Emperor, even if the Emperor didn't hold back out of fatherly love, even if it is very very unlikely.