"Iron-cutlass." A giantess listed among the trollkvinna in the Nafnaþulur section of Skáldskaparmál. Snorri Sturluson makes her the lover of Thor and by him the mother of Magni. He adds that a kenning for Sif, Thor's wife, is Co-Wife of Járnsaxa.
Járnsaxa is also named in Völuspá hin skamma, or Völuspá the Less, as one of nine maidens who bore a man mighty in arms. This man might be Heimdallr.
- Skáldskaparmál, 17, 21.
- Völuspá hin skamma, 8.