You know nothing, Jon Snow (motif)
These lines are constantly repeated by Ygritte reflecting upon the knowledge Jon Snow has about the way of the Wildlings. It soon becomes an expression that is a way of her teasing him in their relationship.
Golden Hand
Jaimie is provided with an elaborately carved golden hand in place for his severed hand. The hand though golden and thus implying power and richness of the Lannisters, is however useless in the field of war as any golden jewelry might be.
Rains of Castamere
After Lord Tywin sacked the Reins of Castamere and killed every single member of their family to set an example of his ruthlessness, the song Rains of the Castamere became a symbol of revenge for the Lannisters. If Tywin Lannister had to threaten someone, he would send a singer to sing the song. The song thus became a symbol of fear people associated with the Lannisters.
The Castaration of the Unsullied
The Unsullied are castrated so as to make them devoid of any human emotions. This is done to make sure that they remain devoid of any human tendencies to plunder and rape while they are attacking a city. This would ensure lesser loss of resources and distractions in the army.
Ice and fire (motif)
Ice and fire amount to a common motif in the books. The northerners often say 'Winter is coming' and speak of winter and the horrors it bring. The people in Essos worship fire and it is often spoken of as a symbol of Daenerys.
