Spaffe: Yes, I know how that goes, I am in the process of getting the same degree as your friend. It is more difficult to find info on the valknot as a symbol than, say, the hammer or the arrows that were worn as amulets. The valknots are, however, readily available to see on picture stones and rune stones. The Christinas back in the day used to mark their stones with a cross or kind of like and X thingy (very technical term, that...), whereas some (note: some) who were true to Odin or the old ways would mark theirs with the valknot. I don't think the valknot was worn like an amulet, like a hammer, though, but I do remember reading about the Rus that Ibn Fahdlan encountered. He was the ambassador from Baghdad to the Bulgars in 922, and while he was there, encountered the Rus, whom he describes as being covered with tattoos from fingertip to neck. He describes the tattos, some of which are trees and just designs (i.e. knotwork and valknots). But you are very right, there is not much at all written about this particular design and it's use. Maybe more to the point is that it has come to take on a certain meaning today, just the same as the swastika has and the Ottala rune, and you might want to remember that if you are planning a tattoo....