Although today it is sadly famous for its appropriation and use by some supremacist groups, the truth is that Nordic Valknut seems to be more related to religion and funeral rites than to politics or other types of issues.
It is a symbol that appears on inscriptions and rune stones, rings, furniture, ships and other objects of Nordic paganism and in territories occupied by the ancient Germanic tribes. It consists of three interlocking triangles whose meaning is not clearly known.
Some scholars such as Ellis Davidson relate it to the Celtic triskel and the symbol of the three legs of the Isle of Man, as they are all tripartite and made up of interlacing. They also relate it to Loki’s and Balder’s ties, and to the paralysis that Odin could inflict on warriors. Others believe that it represents Odin’s horse and his cult in general, as it has been found accompanied by other motifs such as the hanged man, the Valkyries, bears or scenes alluding to Ragnarok. Also, associated with Odin, it could represent the power of binding and unbinding. In this sense it is currently used by Germanic Ethenism or Neopaganism, for which it symbolizes the sacrifice to Odin and his triple nature.
In any case, we don’t know how it was called either. The name Valknut is modern, created from the ancient Norse valr, meaning dead warriors, and knut, knot.
Lynda C. Welch, in her book Goddess of the North: A Comprehensive Exploration of the Norse Godesses, from Antiquity to the Modern Age, says that the triangle is an ancient symbol of the female divinity and therefore the use of three interlocking triangles highlights the female character of the Valknut that would represent the three aspects of the Goddess: mother, daughter and grandmother.
For Kerr Cuhulain, it would represent the heart of Hrungnir, a legendary giant whom Thor killed with his hammer, whose story is told in the second part of Snorri Sturluson’s prosaic Edda. There, in chapter 17, the heart of Hrungnir is described in this way:
Hrungnir had a heart that was famous. It was made of hard stone with three sharp angles, similar to the symbol they call hrungnishjarta (Hrungnir’s heart)
Number nine, which is very present in different aspects of the Nordic tradition, also appears here as the nine angles (three per triangle) of the Valknut. Some scholars believe that they represent the nine worlds of Nordic cosmology: Asgard, Vanaheim, Jötunheim, Alfheim, Svartálfaheim, Midgard, Muspelheim, Niflhein and Helheim.
In any case, the consensus of specialists is that the Valknut is a symbol associated with death, perhaps related to certain religious or funerary practices, or representing death itself.
Among the objects where it appears are an Anglo-Saxon ring from the 8th century AD preserved in the British Museum, a wooden bed inside the Oseberg Boat (Viking funeral ship found in 1904 in Norway), one of the Stora Hammars Stones (four stelae from the 8th-9th century AD in Gotland, Sweden), and the Tängelgårda Stone, an 8th century AD stele also in Gotland.
It also appears in some of the Anglo-Scandinavian stones called hogbacks from the 10th-12th centuries AD in England and Scotland, such as those at Brompton in Yorkshire, discovered in 1867. And on some crosses at Sockburn, Lastingham and Hawsker, also on English soil.
Finally, Alby Stone points out that if the Valknut has to do with the cult and mythology of Odin, then it must have represented something that could not be given but an abstract representation, perhaps because of taboo or because its form could not be imagined.
Sources: Goddess of the North: A Comprehensive Exploration of the Norse Godesses, from Antiquity to the Modern Age (Lynda C. Welch) / The Everything Paganism Book (Selene Silverwind) / Norse Mythology for Smart People / The Knots of Death (Alby Stone) / Wikipedia.