It costs nothing for a nation that is pretty much irrelevant in global military issues to enthusiastically sign treaties against one form of weapon or another. This includes those nations whose only military tactic is to dive behind the skirts of the U.S. or other major military power. Many of those 111 nations fall into that category.

It costs nothing for a nation to sign such a treaty when it happens to have a loophole in it releasing nations from responsibility if they fight alongside a non-signatory nation. Most of the rest of those nations fall into THAT category, including our "NATO partners." Oh, you didn't read about that part on MSNBC?

The amendment as proposed, and those who proposed it, are listed here.

A later amendment confirms this loophole, but requests that those hiding behind it express the proper indignation and hold the required scented hanky under their nose while others die and kill to protect their sorry hairless asses.

I don't know if either of these will end up in the final treaty in this form. The first amendment seems to have wound up in Article 21.