Por que o Oathkeeper Valyrian Steel usa o brasão de Dunk?

Brienne tinha os braços de Dunk pintados em um escudo enquanto viajava pelas Terras Altas e Terras Fluviais

Depois de ser acusada de assassinar Renly, Brienne estava viajando para o norte para tentar encontrar as filhas de Lady Stark e protegê-las. Depois de ter sido dada Oathkeeper por Jamie, ela não pode mais suportar os braços da casa Tarth, como ela seria marcada como uma assassina. Ela, portanto, recordou os braços de uma casa que ela nunca conheceu, que por acaso eram os de Sor Duncan

The arms of Tarth were quartered rose and azure, and bore a yellow sun and crescent moon. But so long as men believed her to be a murderess, Brienne dare not carry them.
_{A Feast for Crows: Brienne II}

"You did beautifully," she said, when the woman showed her the freshly painted shield. It was more a picture than a proper coat of arms, and the sight of it took her back through the long years, to the cool dark of her father's armory. She remembered how she'd run her fingertips across the cracked and fading paint, over the green leaves of the tree, and along the path of the falling star.
_ibid.

Em Uma Festa Para os Corvos , Brienne tem um novo escudo pintado, usando um desenho que uma vez viu em um antigo escudo no arsenal de seu pai - e esse desenho é Duncan, o Alto, sugerindo que ele acabou em Tarth.

The arms of Tarth were quartered rose and azure, and bore a yellow sun and crescent moon. But so long as men believed her to be a murderess, Brienne dare not carry them. “Your door reminded me of an old shield I once saw in my father’s armory.” She described the arms as best she could recall them.

The woman nodded. “I can paint it straightaway, but the paint will need to dry. Take a room at the Seven Swords, if it please you. I’ll bring the shield to you by morning.

...

The captain’s sister found her in the common room, drinking a cup of milk and honey with three raw eggs mixed in. “You did beautifully,” she said, when the woman showed her the freshly painted shield. It was more a picture than a proper coat of arms, and the sight of it took her back through the long years, to the cool dark of her father’s armory. She remembered how she’d run her fingertips across the cracked and fading paint, over the green leaves of the tree, and along the path of the falling star.”

Então a imagem simplesmente mostra a espada e o escudo de Brienne como eles aparecem em Uma festa para os corvos .