Silver Badge

You get it when the Guild promotes you to Silver, which completes the main quest Tyrant Mulcimer. The promotion plays the first time you walk into Guild Lobby, in Guild Entrance, after you beat Jin in Magma Grotto Town. Nothing checks the badge itself. The promotion is what counts.

Until you're Silver, the people in three of the houses in Capital Downtown throw you out as soon as you step in.

The tougher road tamers come a step earlier, as soon as you beat Jin: from then on, road tamers bring their late-game parties, and Tamer 33 in Magma Grotto South 3, Tamer 37 in Floating Islands Road 1 and Tamer 67 in Desert Road to Rock Tyrant start battling you.