Had an idea...
From what I remember, the DC for poison on "applied poison" bought from shops was always ridiculously low. After reading a post by Sakes about DCs, I think maybe modifying other DCs (if possible) on the server might be appropriate to put yet another thing to better use.
My idea was to have poison DCs and durations increase by +1 DC/+1 round per 2 levels of Blackguard or Assassin.
Don't know if it's possible, or a good idea... just throwing it out there.