Vana'diel Bestiary: Malefic Fencer  

I have fought this guy tons of times. If you go in at lvl 30 to fight him, be ready for a battle. He has a special attack that drains numerous stats, can cure III himself, and will also cast other spells and use other skills to hurt you. You should be able to handle it if you are smart about things.
As for the reward, I usually trade beastman seals and get the 900 XP bonus. I know, some people are going to think that's a terrible idea, but I don't make any money doing BCNM's, so the XP is a good trade. I have seen him give a few different bonuses to items traded to him too. Offhand I can remember I got +3 dark to a piece of armor I traded, which I wasn't impressed with. Then, I got +5 mp to a pair of centurion's boots. I was pretty excited about that. Since the bonuses are "random" good luck to anyone hoping for the mp!