No, lifting the ban for arms sales to China is not a route to cooperation between the East and West, because it is a dangerous experiment that could end in a way. There are often conflicts with Asia, and the EU might just be giving arms to their future enemies. Giving away weapons does not make a society want to be democratic.
The argument that giving the Chinese government weapons to shoot their own citizens with is somehow a road to democratization is just ridiculous. How would this foster an environment where advocates for democracy and civil liberties are free to say what they want and express their opinions? If they knew their government was getting weapons from the Western world, and thus even more tacit support, this would not bode well for such a movement.