User blog comment:B214/Question and Answers 2/@comment-3965848-20140219094943/@comment-16281343-20140220011940

It was just Gram.

Dainsleif and Tyrfing are swords in the Nordic legends unrelated to Siegfried. Balmung and Nothung are other names of Gram.

That's stated in the Demon Sword's Trivia section.