When an assassin is sent, they die bravely in their protection of the royal family.
The noble parents grieve exaggeratedly about how brave their child's death was.
The royal family acknowledges it by sending a medal of honor as recompense to the family, and in this way, Noble and Royal bonds are deepened.
Their very existence amounted to only such a thing.
You could call it a sacrificial pawn, a display piece.