For reference sake these are the ideas I actually suggested back in 2012! The numbers themselves should be taken with a pinch of salt since this was before the game itself came out.
Finnish Tradition grants the Finns 0.25 Land Morale bonus and 10% Cavalry Power, representing their history as the border between the East and the West. Having fought in every conflict between Sweden and Russia the population of the country has been decimated time after time, only for the Finns to serve the crown in the next war.
Sisu: +20% Fort Defense. The Finnish mentality which can best be summed up in "never give up"; Sisu can be defined as thus: Sisu is a combination of something where The Hardest of Truth, The Coldest Of Rationality and The Darkest Of Insanity meet in such a manner where they all (believe or not) serve the same goal to make it all better.
Swedish Legacy: -10% Stability Cost. As a Grand Duchy within the Swedish Crown, Finland had a tradition of remaining calm and even "ideal" as a vassal. The people rarely revolted and the many western notions imported by Sweden only improved on that.
Fur Trade: +10% Trade Power in foreign trade nodes. For much of its history Finland was a major exporter of furs, in particular those from raccoons, squirrels and the like. In fact several counties within the Grand Duchy did not pay tax, but rather furs to the crown.
Tar production:-20% Fleet maintenance. In Middle and Eastern Finland, great amounts of tar were produced. European nations needed this material for the maintenance of their fleets.
Hakkapeliitta: 10% Cheaper Cavalry. The Hakkapeliitta were the feared Finnish cavalry serving under the Swedish Kings.
Army Reform: +5% Discipline. represent the reforms undertaken by Gustavus Adolphus which transformed the Swedish armies to fit the model of Maurice of Nassau
Gibraltar of the North: +10% Trade Steering. With the founding of Helsinki, the city begins to serve as a rival trade power for Reval (Tallinn) a Hanseatic city.
In the end Finland gains -1 Revolt Risk and +10% Manpower Recovery.