If using this skill on yourself, Balthazar's Spirit is superior, due to the fact that the damage type that fulfills the requirement to gain energy is not restricted to elemental and physical and it triggers when you take 0 damage.
This skill is useful when all the damage is being directed at the party's tank(s).
As long as the target ally takes damage at least once every 3 seconds, the bonder will gain more energy than the upkeep cost. As most foes have a faster attack rate than 3 seconds the bonder will usually gain energy even if the target is fighting only a single foe.
Damage redirected to you as a result of Life Bond does not count as physical or elemental damage, and therefore will not give you any energy.
You can also use it on enemies who start friendly and later turn hostile. This is useful for foes who have dialog before attacking, as it will give you energy for damaging them.