It works by powering up your next beam attack barrage, in successful, it'll drain power from Auxiliary. When you say they aren't a high enough rank to use it, you simply need to promote them. Promote them by giving them the required amount of skillpoints for you to be able to do so.
If you match the target subs with a weapon system that has a complimentary proc like polarons it can make them more effective as well. But of course you cant rely on a proc .... its just a nice suprise when the two happen to work at the same time.