He used a sharp instrument instead of a blunt one.

Into the vein itself with a sharp instrument or around the vein with a blunt instrument.

This area can be envisioned as a sphere with a person and a sharp instrument at its center.

When demineralization of enamel occurs, a dentist can use a sharp instrument, such as a dental explorer, and feel a stick at the location of the decay.

Her first patient sees the sharp instruments and balks at another treatment.