I did indeed, however he did not truly beat him up, but blocked his attack and shredded some of his gear. Corax then thought it was wise to leave said situation.
No...he didn't "shred some of his gear". Curze talked some smack to a Corax who had just been dueling Lorgar. Lorgar was the one who damaged Corax's gear.
Corax then flew off.
In short, Curze didn't "beat him up". He blocked an attack and talked smack to him...and that's it.
Ok cool then. Thanks for reminding me it's been a while. Still doesn't explain why Corax has a lower WS