http://wiki.project1999.com/Disciplines
Counterattack (53) or Nimble (55) are decent to same yourself every once in a while to make a run for a zone line or tank for a moment while a heal spell is cooking. Really though you'll just use Duelist at 59+ for burst DPS.
Double Backstab at 55+. Does what it sounds like.
Sneak/Hide improves in regards to the speed you can crawl along. Goes up to about 90% of normal run speed at 60.
At 51+ Bind Wound can go to 210 skill, so you can bind wound up to 70% hp.
Assassinate allows for a random 32k backstab on a humonoid mob level 45 or below.