If the next Halo Game allowed you to choose from multiple characters in custom games I would want certain assassination weapons for each species just for aesthetic use only.
Elites: Energy Dagger or Curveblade
Brutes: Jiralhanae Combat Knife
ODST: Humble Stun Device or Combat Knife
Spartan: Combat Knife, Katana or Machete
Knight: Blade Arm
Remember it's for aesthetic use only and doesn't change the game play.