VALKNUT

This symbol is a Valknut. The Valknut was the special symbol of Odin, king of the Norse Gods. It consisted of three interlocking Triangles, but if you removed any one of the triangles then the other two would fall apart and would not be linked together at all.
The Valknut symbol is often found on Viking stones where Odin is depicted going into battle or standing over fallen warriors. It’s not hard to see why the symbol would be synonymous with strength in battle: the three interlocking triangles symbolise the strength we have in acting together which falls apart when we go it alone
The valknut is a historical symbol worn by warriors during the Viking age. Even more so, this symbol was worn by warriors who were willing to give themselves as a sacrifice to Odin on the battlefield. The symbol effectively means “I give my life to Odin; he may take me whenever he wishes” You should only wear this as jewelry or a tattoo if you are devoted to Odin and want a place in Valhalla, it is the token of those who are given to Odin and should be worn only by those who are willing to fall at his choice.
If one has a valknut permanently placed upon them as a symbol of their devotion to Odin, they are declaring themselves as a sacrifice to him should he feel the need; whenever and wherever. That is not something to be done lightly.