A more extreme idea is to make each government's fleets be limited by a portion of economic power and ignore dreadnought limits entirely. it's not super popular, but it is an idea.
The problem as I see it with the treaty of Farixen at all is that it imposes strict limits on the size of the self defence forces of nominal allies. If one were to limit fleet size in general, that would lead to even more kicking of the quarians, and even more resentment of the self-declared most important species of the universe. "Just mothball a chunk of your fleet," is easy enough to say when you're not in a war with the slaving, marauding savages at your borders.
Don't confuse my annoyance at the treaty with annoyance at you, however. It simply always struck me as stupid that the turians massacred exploration and science craft, waged war against humanity, and humanity simply leapt at the chance to sign a treaty limiting their number of dreadnaughts to a maximum of ten percent of the fleets of the council trifecta. All that, and people still bitched about Gen. Williams' surrender at Shanxi, while the Council lulled humanity into the stagnant society at the core of Citadel space. "You don't need military, you've got turians for that..." seemed to be the general sentiment, but that was of course not actually the case.
Relations between the Batarian Hegemony and the Systems Alliance have always been cool, and with humanity not being used to getting their colonies razed and inhabitants enslaved, it was only really a question of time before war was declared. Batarians are of course widely known for always following Council laws and treaties, so any engagements would be completely fair, no? Imposing sanctions on humanity becomes doubly important, to allow the poor batarians to express their culture. Snerk. Humanity bowing to the Council, but not getting anything more than platitudes in support now sort of annoys me.
Usually, signing a treaty where you agree to disarm, limit your weapon production or similar means one of two things: You lost a war, or the other side is also limiting itself in some manner. The treaty of Farixen is basically a way of ensuring that no upstarts will ever become military or economic superpowers in their own right. If anyone wants protection, they can ask the turians for help, but will then be made client races. Dreadnaught are first and foremost meant for two things: killing opposing dreads and projecting military force. This is not something the Council wants other powers capable of.
In Mass Effect (the first), Udina complains that an enemy of all the Council races attacked Eden Prime, and the response was more or less "Tough shit, but that's what you get for being a buffer nation. Also, we trust our nominally loyal loose cannons much more than your navy officers.". Agreeing to restrictions imposed on them by the Council, allowing foreign agents the ability to take unilateral action against nebulous 'threats to the Council' in their space. The Council is basically space-EU, only worse, somehow...
Humanity was always expansionist, and a well developed military is part of that, especially in the Terminus. I do not believe humanity would accept anything but a relaxation of the restrictions of the treaty. If the Council asked the SA to disarm in the middle of a war for sentient rights, the SA would probably just tell them where to stick the amended treaty. I don't want to seem like a Humanity First member, but it seems like at every turn humanity has had to give up liberties, with nothing but 30 square meters of embassy to show for it. An expanded market can be good, of course, but that also means competing against the races with an actual say in trade law, which is less than optimal. The war against the batarians might be the final push that makes humanity go "Those guys are assholes, let's do our own thing."
