Baffle says :
Vital Shock is a direct damage perk that usually do 2-5k ish damage. It also works like a lifetap. You get ecactly 75% of the inflicted damage back as a heal.
Usually the damage is around 2500, something that give you a 1875 heal. You need to be level 205 to train this perk. (People usually train it at 206 to be able to have the Easyshot/VitalShock combo)
Vital Shock stun the target in 3 seconds. The effect is actually a calm that breaks then you shoot at the target again..
The distill life perkline aslo increase the power of your umbral wrangles slightly. Example: A +140 umbral and +10 distill life turn into a 147 umbral.