That Random Guy

So a friend and I are making a hack and in that process, we thought of some OP weapons that we wanted to make difficult to get, and so we wanted to put a level requirement on them like "Pale Flower of Darkness" or "Four Fanged Offensive" in Fe7, and couldn't figure out how to do so. If anybody knows how to do that, or at least knows if it is impossible in FEBuilder GBA, any help would be appreciated.