Yes it a symbol of the dead or the slain, although its exact meaning has never really been determined... The # 3 is a mystical # in many cultures, even though the Vikings heralded the # 9 as being the most significant #..The nine worlds, nine days Odinn hung from Yggdrasil, where he learned 9 powerful songs and 18 runes...
I have never heard of any groups wearing the Valknut , but I live in Aussie and we don't have the dramas here that you have, wherever you are from obviously...
Wear you Valknut with pride and if some clown accosts you for it, simply say it is an ancient and sacred symbol to the religion I follow and that my religion is far older than any neo-racist, or whatever group which may have adopted our symbol in recent times... Make sure you are diplomatic as you don't want to get yourself into a violent situation...
I have a white Valknut at the bottom of my shield, in the middle,below the boss, with both Odinn's ravens above the boss, each side, that is my "signature",a sort of coat of arms" so to say...
Follow you path with your head held high...
Hann til ragnaroks...
In Light... )O(