User blog comment:B214/Question and Answers 3/@comment-25222726-20140704142303/@comment-16281343-20140705071151

So does the BG,DD, and the other Longinuses that can kill Gods. But no one has done that yet (at least none has been revealed to have done so).

Having the TL doesn't mean you can kill them with no problem. It only gives you the means or the chance to do so. The possessor still needs to train and achieve power that is close to an Ultimate-class / high-tier High class Devil (example is Vali) to do so.