Eihwaz might go as far back as the Proto-Indo-European term eiwos and means “yew tree”.
We learn from the Anglo Saxon Rune poem composed in the 8th to 9th Century, that the yew tree is a “guardian of flame”, possibly of knowledge and insight and it is often associated with Yggdrasil which (even though often said to be an ash tree) have have been a yew tree in earlier myths.
The yew tree has often been associated with burial grounds, death and travelling the Underworld. It’s a Rune of the cycle of life and nature, of birth, life and death. The Underworld was no christian hell, but rather, a realm of transformation, of change, and of new life at times.