What am I?

1. Don't touch me unless you are well skilled and qualified.
2. I can be dangerous but in the right hands I can help animals.
3. My three razor sharp blades are contained in a flat brass container.
4. Each of my blades is a different size and is hinged at the top of my container.
5. Vets once used me but I could still be useful!

Answer in next week's TreasureLink!