Kylee is correct. ONLY job level affects upgrade success. I've played a Whitesmith on various servers for about 3 years now, so trust me on this! Dex and Luck affect forging success, that's all. Nothing affects the success of the NPC refining something. Not Weapon Research, not dex/luck, NOTHING. Think about it...you're giving the NPC your item for him to upgrade it, so why should your stats have anything to do with his success? Oh and by the way, Whitesmiths can only upgrade weapons. If you need to know any more about my favorite class, check out the link for a guide I created on playing a Whitesmith. Hopefully it will be useful to you:
http://www.pizza-ro.com/forum/showthread.php?t=176