(1) If the ox falls, whet your knife. 

(2) A blunt knife may be sharpened on a stone, but if a man is stupid there is no help for his stupidity. 

(3) He is wielding a knife.

(4) We eat with knife and fork.

(5) The knife has a horn handle.

(6) Hold the knife at an angle.

(7) He used a knife instead of chopsticks.

(8) Trim rough edges with a sharp knife.

(9) This knife cuts well, doesn't it?

(10) He made at me with a knife.

(11) The knife easily cut into the cake.

(12) He held the knife to her throat.

(13) She was confronted by a man wielding a knife.

(14) He slit open the envelope with a knife.

(15) The knife pierced through his coat.

(16) He jabbed at the lid with a knife.

(17) She was sawing the bread with a blunt knife.

(18) I cut myself on a knife.

(19) Trim off the excess pastry using a sharp knife.

(20) He wrested the knife from the murderer.

(21) Scrape the mud off your shoes with this knife.

(22) He picked up his fork and knife.

(23) The mad man came at us with a knife.

(24) The knife penetrated his finger.

(25) He thrust at me with a knife.

(26) a knife with a sharp edge/blade.

(27) May I use your knife for a while? Sentencedict.com

(28) He'd been stabbed four times with a kitchen knife.

(29) The knife cut the flesh of his arm.

(30) She scraped the rust off the kitchen knife.