I know the school of the Swordsman mentions the rumor of secret vis techniques for Tremere. Are these rules spelled out anywhere or is it just a story hook waiting to be clarified by a SG and Troupe.
IIRC, the later. I have not seen rules for this anywhere.
In earlier editions of the rules, and to a lesser extent in this version, Tremere get special virtues which make them good at certamen. In-game, the magi talking to each other can't say "Oh, you have the Affinity Virtue in Certamen". These bonuses were justified as secret techniques.
Personally, I think the Tremere having a mathematical bonus in Certamen makes it really likely the rest of the Order goes "This is not fair, and so we will not do this." so it's been downplayed in the new edition.
Contests between non-Tremere magi makes Certamen a very useful tool indeed.
Agreed. This is why we suppressed the tremere house flaw. What tremeres have is people that train in Certamen more than other houses, and THEY (and only they) have the Tremere bonus. T>hey are the house champions in case their expertise is needed. The Tremere have the Social Contacts virtue and the Close Family Ties flaw, only that the Family is the House. Make much more sense in our opinion. The social contacts virtue is broader than what the RAW mentions since it effectively deals with the agents and informers that the tremeres have scattered around.
I agree. Not all (or the majority) of Certamen matches are between Tremere.
Anyway, sure, individual Tremere tend to be better on average than individual magi of other houses of a similar age. However, I fail to see why this is a game-breaker. In character, this is just because Tremere have focused their training in Certamen more. Other magi are better at turning into bears or talking to Faeries, or whatever.
Generally, every magus will try to arrange things so that he only fights Certamen against people worse at Certamen than him. When his opponent is a Tremere it just means that his calculation of "is he worse than me" is a bit different to normal. It is still possible for an individual magus to be better than an individual Tremere at Certamen.
For me, the Certamen focus just means that other magi should be a bit more likely to try to negotiate a settlement of differences than actually fight Certamen with the Tremere. For the Tremere it means that they have an advantage in such negotiations, which is good for them. But an individual Tremere probably doesn't want to push things too far --- because he might actually lose a fought Certamen match, or if an individual Tremere proves too good at Certamen then his opponents might decide to bypass Certamen altogether and go for Wizard War instead.