Sword Kirby wears a long green hat like Link's hat.
Kirby's Adventure and Kirby: Nightmare in Dream Land
Kirby usually attacks just by slashing the sword.
Kirby & the Amazing Mirror and Kirby: Squeak Squad
Sword Kirby can use his sword underwater and most commonly used by the other Kirbys.
Kirby Super Star and Ultra
Kirby can use much more attacks then just slashing the the sword. Meta Knight makes'lets Kirby use a sword to fight him.