The armorial banner is a flag based upon a coat of arms. The coat of arms for the Legend of Zelda, which may belong to Link or Princess Zelda can be found on the original game cartridge. The arms consist of a heart in the first and fourth quadrant and a key in the second area and finally a rampant lion facing the hoist in the third quadrant. The colours are unknown since the sticker is black and white.
Note in the game Link uses a cross as his arms, so it is likely the arms belong to the Zelda Dynasty.
Two hearts gules on a background of argent, a lion or rampant facing the fly on a background of dark azure, and single key mostly or and mixed argent on a background azure.
But when the original game cart is in the box the arms have golden bar canton, which you can see here.