Legionaries: Siphon Life Question

[MadEdric]

The Balefire Adapt has the ability Siphon Life that allows for each attack die that you resolve that does damage, heals an operative for 1 wound (or 1d3 wounds if it is a crit).  Using it ranged is easy to calculate as unblocked dice are resolved at the end of the step.  

Using the Fell Dagger is different though, as the attack dice are resolved individually and in a back and forth fashion with the opponent.

Basically in the last game this happened:

Adept gets hit for 6 DMG, this takes him down to 5 wounds he retaliates with a crit and heals 1d3 for 2, raising his wounds to 7.

He gets hit again for 6 down to 1 wound, but retaliates with another crit and heals again to 4 wounds.

The fight was over after that. Note, without the healing from Siphon Life, he would have died

Was this the right way to run the fight? Healing after each attack dice was resolved, or should the healing be done after the fight (which would have had the Adapt dead)?