Notes from author
This build should be useful both PvE and PvP, but if you're having a though time, I recommend farming some Resin.
Always buff your weapons in boss fights, it can be really hard to make damage because most bosses won't bleed because you won't have the time for it.
You'll have to change something to use a catalyst.
Shadow Set may be more useful in some situations for its high bleed and poison resist.
Remember that Thief's set is only better then Shadow when highly upgraded. Shadow set is easier to upgrade too.
Have fun.