Cluster bombs scatter and leave a wide swath of destruction when they land. With modern technology and laser-guided munitions, there is no need for cluster bombs anymore. This isn't the Vietnam War era. A ban is good enough for everyone involved as cluster bombs won't win any wars because they are outdated technology from 20 years ago at best. Modern militaries have much more advanced munitions.
Bans on particular weapons like cluster bombs should apply to both signatories and non-signatories, and be enforced by all nations. This should not be flexible, as the end goal of any gathering of the countries is in the best interests of the world as a whole. Furthermore, there is very little need for cluster bombs.