A kirpan is a real forged steel blade, single edged or double edged, ranging from a few inches to a full sword, and it is made by a blacksmith or bladesmith rather than a jeweler, the same trade that produces any working knife.
Wearing it
The blade sits in a sheath, usually worn under clothing on a strap called a gatra or fixed to a belt, and its size is a matter of personal and community practice rather than fixed doctrine, some Sikhs wear a small symbolic blade only a few centimeters long, others a functional short sword. This is one of the Five Ks required of a baptized, Khalsa Sikh, and it is worn continuously rather than reserved for ceremony, which is precisely why its legal status as a weapon has been contested in schools, airports and courts in many countries.
What happens to it over a lifetime
A kirpan is generally kept for life once a Sikh is baptized, replaced only if lost, broken or outgrown, and there is no requirement to discard an old one as ordinary scrap, many are kept as family objects or passed down. When a Sikh dies, the kirpan is commonly left on the body for cremation along with the other articles of faith rather than removed and reused, treating it as inseparable from the person who carried it rather than as reusable equipment.