Though most of the nobles that entered Grenton died, some actually survived. These people were the ones who had no more intention of getting Valdel's weapon. After learning that Valdel had a ring with the emblem of the royals, these nobles decided that the risk of offending Valdel was too much for them to handle, so they left the town as quickly as possible.
Before anyone says that another one about killing the whole family type things. Please understand even back in the day when a certain faction is known to be traitorous the emperor or king would kill the whole family, or sell them off as slaves. ALSO you must remember that this is also in a FANTASY setting with a different kind of environment. So the actions and factions are different than that of the real world, so the solutions are different.