1.   His knife had slipped and sliced off the top of his finger.

2.   His knife had slipped and sliced off the tip of his forefinger.

3.   The knife slipped and gashed his finger.

4.   The knife slipped and cut his finger.

5.   However, not only is this somewhat dangerous as the knife can slip, it will also produce a flavorless, water-logged onion.

6.   The knife slipped.

7.   The knife invariably would slip out of the hook in his prosthesis.