Celtic Heroes

I'm a level 65 rogue thats pretty evenly distributed stat points across all four areas. I figured that each has its own merits, but then noticed people putting emphasis on only certain traits. How do I improve point distribution?

I use QS, sneak attack, assassinate, double attack, plus other various healing, etc.

I need to be able to maximize attack by cutting unnecessary points on other traits. Thoughts and tips are appreciated.

Most people use QS, shadowstrike, riposte, and lifesteal for skills. Shadow is usually real expensive but worth saving for.