My main in LOTRO is a much beloved Burg and I couldn't stay away from the thief class in GW2, so I have switched my main to my Thief, and his trait lines at level 37 are:
Deadly Arts (10) - Serpent's Touch (Stealing applies poison for 10 seconds) - Sundering Strikes (40% chance to cause vulnerability for 5 seconds on a critical hit)
Critical Strikes (7) - Keen Observer (Critical hit chance is increased by 5% while health is over 90%)
Trickery (10) - Kleptomaniac (Stealing gives you 3 initiative) - Flanking Strikes (Increase Damage by 5% when attacking a foe from behind or the side)
I run double daggers with Hide in Shadows, Roll for Initiative, Radiation Field, Signet of Agility, and Thieves Guild equipped. I focus predominantly on stacking Precision and Power, with Vitality as the preferred backup stat.