Quote from Cryosite;280277:
Emporium mod > blade refinement 5. The fact that 15 str and 50 luck with artisan upgrade matches emporium mod (hp and stamina a trivial bonus on top) means that artisan is probably superior to blade refinement 5 even easier (claymore is good for crit, and blade refinement 5 lowers crit). All you'd need is minimum luck and 15 str from artisan upgrade to beat it. Since 15 str is half the possible range for it, then about half the time artisan upgrade will be a better choice. If you are able and willing to purchase one or two of those artisan reset deals from the cash shop, you can pretty much gaurantee superior results.
Half of the time assumes that you get Str modified all the time, so in reality it's less than a half chance. Remember that alongside variable amounts, getting the bonus in the first place is also variable.
And along with Animefreak, if there's a place where we can find the Artisan upgrades without sifting through pages and pages of google translate, could somebody provide the link?