The Visitor Event Guide/Discussion.

Could someone briefly explain the rewards?

From what I've gathered, we get 4 pieces of armor - overall, hat, glove, and shoe - and these can be scrolled. They have more slots than most items, but they're not permanent; they can be made permanent, but no one knows how. And you get these items during stage 2, which isn't available yet, but some people still have these items (somehow).

Right?

Pretty much right. Except people got them because Stage 2 was activated for a short amount of time before the Server Maintenance last night, which deactivated it.