Tailor's awl or alder: anti-slip, ergonomic and wonderfully sharp.
Poke holes in leather, fabric, etc.

When do you need that?
For example, to attach a buckle, the pin (that is the rod that goes through the hole) must go through the fabric. Or when using snaps, the destructible ones such as the Anorak snaps or decorative staples in jeans, etc....

Also useful as an extension of your fingers to guide something nice and flat under the presser foot, without tucking your fingers under it.

Also for English embroidery, also called Broderie Anglaise, hole embroidery or open white work