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Tommy Dunne, weapon master for Game of Thrones, is seated here with several weapons on display. Most notably, of course, are the sheathed greatsword belonging to Ser Gregor Clegane and Eddard Stark’s ancestral sword, Ice.
Clegane’s sword is quite massive, and is later described as being 64 inches (1.62 meters), while Ice looks to be about 60 inches (1.52 meters). The pommel, with its pierced ring, is clearly inspired by the Irish ring hilt, and I believe the cruciform guard was not unknown to Irish swords of a similar period, which date from the late Medieval to Renaissance. There’s an excellent discussion about swords like this at My Armoury.
Behind Dunne we can see several other weapons. One of them—the one whose hilt is pointing towards Ice—is in fact Arya’s sword, Needle.