[Rumil]

I guess one benefit of leaving orcrist on top of Thorin's tomb was that the Dwarves could tell if orcs were close to the Lonely Mountain by the gleam from the sword (as for Sting), and so avoid being surprised.

I'd imagine some sort of very solemn duty guard of dwarven soldiers guarding the tomb of Thorin and able to raise the alarm if Orcrist lit up, must have been exceptionally boring!