A month or two ago a similar weaver built a nest on this same branch in our garden. Unfortunately, the nest wasn't secured well enough and it slid off the end of the branch and ended up on the grass below.

I've watched this weaver build its nest over the past few days and, perhaps it's premature to say so, but I think it looks a little more secure than the previous one. That said, I sure hope that the little piece of grass that you can see wrapping over the thorn above the nest isn't the only thing keeping it in place!