There are so many arms sources, America being the number one place. Of course they would probably want to buy from countries other than America because we tend to make inferior products anymore. EU is doing nothing but cutting off a source of income and handing it to another country.
Weapons have become more sophisticated, but so have weapons producers. Technological capabilities exist throughout the world, so the EU ban on sales to China has little effect. Not only could China buy weapons elsewhere, but they have the capacity to build their own weapons. In fact, the EU arms band might even convince them to acquire those arms sooner.