Even if they are not always followed or if the policy is seen as ineffective, the arms ban is still a relevant symbol. Bans are an important symbol for the international community and it shows a world wide consent that the countries policies are negative and should be curbed. Therefore, the ban is still a relevant symbol.
Yes, the EU ban on arms sale is a relevant symbol of a lack of tolerance for China's human rights abuse. It is important to allow China's economy to develop through trade, but still have a way to take a symbolic stand against China's human right abuses. The ban on arms sales allows for this and also provides a method to prevent China from gaining too many weapons.