The description for the Fortification ability is the following:
Reinforce armor using protective Foucault currents. Purge the current and send its charge to your gauntlets for increased melee damage.
Slow down power use.
So deactivating (or "purging") Fortification gives you a melee damage bonus for certain duration.
My question is, if I immediately reactivate Fortification again to gain back the defensive bonus, do I then cancel the melee damage bonus that I just triggered?