一刀[ittou] sword
一刀彫り[ittoubori] one-knife carving
一刀両断[ittouryoudan] cutting in two with a single stroke
印刀[intou] seal-engraving knife
円刃刀[enjintou] round-edged scalpel

快刀[kaitou] (literary) sharp sword
快刀乱麻[kaitouranma] solving a problem swiftly and skillfully
懐刀[futokorogatana] confidant
儀刀[gitou] ceremonial sword
軍刀[guntou] saber

快復[kaifuku] restoration
快い[kokoroyoi] pleasant
快楽[kairaku] pleasure
快楽主義[kairakushugi] hedonism
快濶[kaikatsu] cheerful

快感[kaikan] pleasant feeling
快挙[kaikyo] brilliant achievement
快哉[kaisai] joy
快作[kaisaku] splendid work
快事[kaiji] pleasure