What is it?

[metalsmith]

I chanced upon the following at a car boot sale and thought it was worth the chance for the 50p I paid for it as possibly being a carbide-tipped engraver / similar. My knowledge on the subject is 'zip', so if anyone can help before I continue on to try ramming a square peg into a round hole...

Anyway, it is triangular, approx 130mm long with a couple of (home-made) foam rubber grips. The 'tip' is maybe 12 or 13mm long...

Thanks for your help!