It is fairly well established that Arthur Dayne is the Kingsguard that wielding two swords, however in the books we are told there were three members of the Kingsguard present:
He dreamed an old dream of three knights in white cloaks... They were seven facing three, in the dream as in life... Ser Arthur Dayne, the Sword of the Morning, had a sad smile of his lips, the hilt of the great-sword Dawn poked up over his right shoulder. Ser Oswell Whent was on one knee sharpening his blade with a whetstone, across his white-enameled helm the black bat of his house spread it wings. Between them stood fierce, old Ser Gerold Hightower, the white Bull, Lord Commander of the Kings Guard. - A Game of Thrones, Chapter 39
- Arthur Dayne
- Gerold Hightower
- Oswell Whent
In the show there are only two...
My guess is that the second is Oswell Whent because in the opening scene he is shown "sharpening his blade with a whetstone" and is not "old". Can this be confirmed through scripts or credits?
Bonus question that I know might be answered in the next episode, or is just a cutting of characters as D&D are want to do: Where is Ser Gerold, being Lord Commander, one would think his inclusion would have had more impact...