User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-5590366-20121007162553/@comment-4918650-20121007184914

Now that you mention it, it did say that and it reminds me of the line from the prophecy:

An oath to keep with a final breath.

It could be Frank's last breath. And when they freed Thantos he had to burn the "life stick" to free him.