As I've read them (I currently play a Tremere), those extra rules are for specializing your Tremere in distinct 'schools' where you trade one thing for the other. Exampli Gratia: School of the Hoplomachus - the practicioner always loses initiative, and may subtract up to his Finesse score from his Attack, but adding twise this value to his Defense. In effect, by trading in the initative, the practicioner can duel very defensively, to begin with, and perhaps guage the opponent's strength, to adapt his own fight.
My ideas some time ago, about certamen, was that I wanted it to be a lot more like Dimicatio. Instead of using the same 2 arts every round of duelling, with only which one is for Atk and which is for Dfn as variable, I'd want all arts to be possible. The Tremere still have a Focus with this, doubling the lower of the relavant arts. And magi good at various attack and defense spells will do good in this duel.
Magi in the duel use a 'shadow' form of magic, one that does not damage or affect the enviroment, like regular magic does. Either Spontaneous-like magic (but not halving for fatigue use, dividing by 5 for not - something else which I haven't quite figured out) or Mastered Formulaic spells, where the magus took the a mastery called 'Certamen' Perhaps even a two-tiered ability, where you need Mastery 2 with both Certamen Use and Certamen Attack for it to work. The idea is for the 'Formulaic' spells to be better than 'Sponting', so I need some divisor/penalty for totals when sponting, but not /2.
So initiative is determined as normal. Faster magus attacks, slower magus needs to try and whip up some defense. He needs to obey the normal rules for fast-cast defense, reagrding Form/Tech vs. what the attacker did. Perhaps there should be some bonus if using a Formulaic spells known with the Fast Cast Mastery, as well as Certamen Use. If an attacker lands a spell on the opponent, it deals Fatigue loss, rather than the normal spell-effects from normal Hermetic spells. This fatigue loss ought to be based on Penetration, because this forces the attacker to make tactical decisions. Should I cast a high level spell, which is difficult to defend against, but less likely to Penetrate, or deal much Fetigue loss? Or should I try for maximum Fatigue, but risk having the opponent defend?
I'm still struggling with these ideas, and think best 'aloud'. I apologize to the OP for going OT.
But to adress this, perhaps Warping is too steep a penalty to suffer. House Tremere would IMHO be seriously nerfed.