A Link to the Past
The Sword Knights are the sword variation of the Knights. They are first encountered inside of Hyrule Castle Tower on the way to Agahnim. They are wearing a blue armor with horned helm, and carry swords as their weapon. Unlike weaker Soldiers, Sword Knights are more powerful and attacks with more dexterous. They will immediately charge at Link when they see him enter the room. They can be dealt with by repeatedly slashing them with the sword.
Four Swords Adventures
The Sword Knights in Four Swords Adventures wearing a green armor with helm without a horns. They behave the same as they did in A Link to the Past. They can be found guarding the Hyrule Castle.