Pairs of seven.
*By George R R martin
**As for the Starks category, they have to be born a Stark and be alive as of GoT.
Source: http://awoiaf.westeros.org/
If you are going to have Oathkeeper, you should also have Oathbreaker - Ice was so big it had enough steel to be forged into two swords.
I also think that the epilogue/prologue characters are confusing, as I immediately thought of Pate, who is the only person who fits the bill perfectly (both a prologue and an epilogue character, even if it isn't "him").
I agree with the wording thing, but you're wrong about the swords. Ice was reforged into two weapons, a sword given to Joffrey that he called Widow's Wail and a longsword originally given to Jaime but given his condition he gave it to Brienne and had her call it Oathkeeper. Both of the swords are listed correctly in this quiz.
I also think that the epilogue/prologue characters are confusing, as I immediately thought of Pate, who is the only person who fits the bill perfectly (both a prologue and an epilogue character, even if it isn't "him").