I have a warrior on this playthrough and I have the abilities from the reaver and berserker activated, the reaver one normally "eat" away some of your health in return for some bonus and the berserker one normally increases your damage level for some period of time, with the trainer options 1-4 (or 1 of them) activated the damage goes to 999.999 per hit and the hero dies instantly (at least that is what happens to me) the dif level influences it as well from what I can tell...
i have no idea what a 'reaver' is, nor is there anything writing 999,999 to the health of any characters (at least not intentionally), nor do i know what you are talking about with bonuses and berserker, etc.
so i am at a loss as to what you are describing. perhaps you should make a save of your game, post it online, send me a PM of it, and then a detailed instruction on how to reproduce the problem here.
best,
Cal