The Hand of the King is the most powerful appointed position in the Seven Kingdoms, second only to the King in authority and responsibility. The Hand is the King's closest advisor, appointed and authorized to make decisions in the King's name. The Hand of the King is the highest-ranking member of the Small Council, and leads meetings of the council as proxy for the king when the monarch is absent.
This has turned into a death sentence for many that are chosen for this position , due to a never ending power struggle in Game Of Thrones.
You could use the tiny sword as a weapon to poke someone in the eye if you had to, or use it to pick a lock.
Ned could have lived and escaped !
In the books I am told it is not a pin but a chain necklace.