Trading unlocks in Blox Fruits once you reach Level 700 and enter the Second Sea, giving you access to the Café as your first trading location.

Two sides of a trade can differ by up to 40% in value under normal circumstances, though that cap rises to 80-100% when permanent fruits or game passes purchased with Robux are added to the trade.

No, you can't trade swords the same way you trade fruits, since Blox Fruits' trading system only allows fruits and game passes to be exchanged, weapons and other items aren't tradeable through it.

Yes, game passes bought through GameBoost work the same as ones bought directly through Roblox, with no difference in functionality once they're applied to your account.