It wont directly save your life, but that isn't the benefit
With the life leach trinket + 2 set you can put out some insanely high levels of self healing as a Warrior. This reduces the load fairly dramatically on healers that can then focus more on the raid and not keeping the tank up and that may not save your life but it WILL save your raid members lives during an AoE intensive situation
It also has the benefit that albeit small, it does in effect reduce the amount of damage you would appear to be taking to a healer by instantly healing up that 30% of the blocked damage