so I finally fought Morganthe today and I used the chest to get my athame (fire) but it took so long because I was getting other schools gear. I get several storm decks along with some balance. I got the ice, myth, and death athames, and I got the storm amulet. Morganthe should just drop the gear belonging to your school not all of them.
Although that sounds incredibly convenient, that also seems a bit too easy. If it were like that, you would only have to fight Morganthe once, and even though I haven't fought them yet, I wouldn't want things to be so easy.