Thurisaz is a Rune connected to the Giant races as well as to Thor. It has protective as well as harmful properties that can be used to attack an enemy.
Anglo-Saxon Rune Poem
Ðorn byþ ðearle scearp; ðegna gehwylcum
anfeng ys yfyl, ungemetum reþe
manna gehwelcum, ðe him mid resteð.
Thorn is very sharp; for every thane
who grasps it; it is harmful, and exceedingly cruel
to every man who lies upon them.
Norwegian Rune Poem
Þurs vældr kvinna kvillu;
kátr værðr fár af illu.
Thurs causes the sickness of women;
few are cheerful from misfortune.
Icelandic Rune Poem
Þurs er kvenna kvöl
ok kletta búi
ok varðrúnar verr.
Thurs is the torment of women,
and the dweller in the rocks,
and the husband of Vardhruna.
The Rune Poem Stanzas for Þurisaz are rather cryptic but the two central concepts as well as the shape of the Rune Stave give us a solid base to work with. The Anglo-Saxon Rune Poem calls it a thorn and the shape of the Stave very much confirms that notion. So in nature thorns are a means of defense, especially in the plant kingdom. This notion is also very present in the medieval fairy tales that were often heavily based on the old Mythology as is perfectly illustrated in the tale of Sleeping Beauty.
The word Þurs on the other hand refers to the Giant races that inhabit three of the nine worlds in the Norse cosmos. They generally represent the forces of chaos and destruction, on a more practical level untamable forces of nature like floods, earthquakes or glaciers and on an individual level subconscious energies and programs that can actually harm us, like irascibility or addictions, if not channeled properly. The one who is responsible for doing that in the Mythology is Þor, who uses his hammer Mjölnir to keep these forces in check thereby protecting Midgard and Asgard, the world of the humans as well as the world of the Gods. With that we come full circle and once more arrive at the protective qualities of this complex Rune.
So Thurisaz can be used to protect and to attack. It can help us to discover destructive patterns in our own lives so we can address them and become happier and healthier human beings. It is also a Rune that can help us to connect our consciousness to the Giant race or to forge a closer connection to the God Thor.