According to the poet, what disadvantages is Grendel's mother under as seeks her revenge?

Beowulf finds an ancient sword left by giants which can slay mother.

Grendel's mother's greatest disadvantage was that Beowulf was wearing armour.

"But the mesh of chain-mail on Beowulf's shoulder shielded his life, turned the edge and tip of the blade. The son of Ecgtheow would have surely perished and the Geats lost their warrior under the wide earth had the strong links and locks of his war-gear not helped to save him: holy God decided the victory."