Hey, sorry for not replying earlier, I've been having problems with ENWorld lately.
Both are good, although the second one says "fiend" a bit more... If we drop the oversized fangs, I think we're there somewhere.
As for describing Sammael... angel of death, brought down by ambition, sees eternal punishment as a reward; ruthless, with a dual nature (still seen as angel by some, devil by others), the most handsome of all devils (hey, I didn't make that one up), as likely to help mortals (sin by association with a devil) as to destroy them. Sometimes mixed up with Satan/Lucifer.