ZAX

Set to 2 different clues across 3 published puzzles, most often “Slate-cutting tool” — The New York Times, Thursday, 16 September 2010.

3 letters

Every clue on record, most used first

Slate-cutting tool2 times
The New York Times — Thursday, 16 September 2010
Hole-punching tool for a slateronce
The New York Times — Thursday, 7 February 2008