Wilderness Medicine (52) - Makes your
Mend Pet heal 15% more of your pet's health, which is a ~42% increase. This is a significant increase, which just means your pet can tank more enemies at once while leveling. This is not exactly a problem to begin with though, and will only be really noticeable if you are doing huge pulls while leveling.
Disruptive Rounds (54) - You get 10 focus back from successfully dispelling.
Improved Traps (56) - Reduces the cooldown of your
Freezing Trap and
Tar Trap by 5 seconds.
Improved Kill Shot (58) - Increases
Kill Shot's crit damage by 25%. This is a nice DPS upgrade, but just means Kill Shot will hit harder sometimes.