I do have some problems with the execution though. I have no idea why the Xindi decided to send a test weapon to Earth. If you're planning to wipe someone out with a single weapon, you don't send a prototype that can't do that. It alerted the Earth to the fact that someone was trying to wipe them out. I think it would have been smarter to have had the Xindi send their weapon to Earth, have it do more damage but fail because it was rushed out. That way, they aren't made to look stupid for alerting Earth to their intentions.