Rares are items which load at a vastly reduced rate compared to others in the game, usually on difficult smobs. The rent cost of most, if not allVerify? rare items is 500 coppers/day.
An update to the Weapons Guilds system on January 6 2019 introduced the ability to craft certain rare weapons, most new, at certain locations in Sidona, in Saldaea, and the Dark Fortress.