I can't speak for the general origin of the name Razvan but I know that I was named after a Romanian folk hero, Razvan Razvatescu. Might try to find more info about him if possible.
Razvan is indeed Romanian. I also tried Razwan, as in most languages the 'v' and 'w' are interchangeable. Razwan is an Arabic word meaning 'keeper of the vineyard'. that's all i know.