I'll just say that as long as he has the medal he gets the plus. Once the medal's gone, it's bonus over.
I would need to increase Military Tactics in rank in order to fill the empty holes left behind. One thing I could see him having is Battle Continuation or Disengage, since there's a particular battle where he should've died but didn't.
The idea is that he doesn't need to pump mana in because that's what the medal is, a huge densified mana disc that only needs an small amount to be lit. It adds one rank to the Phantasm... so C+ is a B rank and a B rank Phantasm is an A++/+ normal attack, which is the intended effect.
Plus, these guy has terrible compatibility against Berserkers of all kind (he can't read an opponent that fights head on) and almost every Assassin you can find. I know who should kill him.