Along with a tree (Yggdrasil), the Valknut is a primary symbol of the faith.
For some it represents Odin, Frigga and wisdom. For others it even represents the three earth goddesses, Ran, Fjorgyn and Hertha, each of whom or often referred to as Mother Nature. But as the gods teach us, these are just labels. Whether you worship or show respect to a symbol, attribute, goddess or god, only worship and respect of nature is truly important in Norse Spiritualism. Worship can be performed in learning and/or protection of nature (wildlife and the environment). On a personal level, people should seek happiness and harmony within their environments.
The Valknut commonly represents mind, body and spirit, similar to the Celtic Triquetra. Unfortunately many vikings in history have given Norse mythology a rather violent picture; so many people associate the Valknut with violence and death. Odin teaches that life is a struggle. The mind, body and spirit will inevitably experience hardship in life, and sometimes between the three. The life-is-a-struggle idea was used by vikings to justify their criminal actions. The vikings were pirates, and they felt they had to believe the gods were mostly on their side. But it is important to remember that vikings were often frowned upon by the majority of Scandinavian citizens. On the other hand, due to over population in places, and being outcasts to begin with, many Scandinavians had little choice but to go viking. Most people throughout history struggled to survive.
A Valknut pendant.