Pruning During Flowering

I am on my second grow now moving into flowering stage.

Does regular light pruning (light =~5leaves) to improve air flow and remove unhealthy leaves impede growth or stress the plant?

You'll be alright

It wont bother the plant.

The removal of damaged fan leaves and lower fan leaves in general during the vegetative phase of the plants should not hinder the growth/development due to the plant being able to produce new ones relatively easier during this phase (vegetative). However in the Flowering phase I would be more cautious on the removal of fan leaves, if they are damaged I see no reason not to remove.
Happy growing.

I knew a guy that only cut off one and a half leaves and it didn't go so well. Before he got Half way threw the second leaf he had a heart attack and shit his pants. So it depends