After a battle with someone who I believe used phased tetryons on me in PvP, 3 of my 8 beams stopped firing. Only the other 5 would fire and show the "3s", "2s", "1s" cooldown while the rest stayed inert.
I think the phaser proc breaks the weapon permanently (for the battle only). After exiting the battle and entering a new one, the weapon works again.
I can't be 100% sure it was the phased tetryons, but assume that it was the cause as I had been in a long battle with one ship using them.