In a typical Role-playing Game like Dungeons & Dragons or Pathfinder, would using a silver plated weapon be good enough to kill a werewolf or other creature that requires a silver based weapon or does the weapon need to be solid silver?
Typically, silver filigree is enough to qualify as a ‘silvered weapon’ for those purposes. The idea is that the silver acts like a poison to the affected creature, not that the whole blade needs to be silver. Also, solid silver weapons unless magical, do not survive combat as the metal is not hard enough.
Indeed, for the most part silver is fluffed as a contact vulnerability. Only the surface of the weapon would need to be coated.
Of course, even with plating over a proper steel weapon, silver can't hold a good edge. Which is why most games have silvered weapons take a damage penalty.