Have you ever noticed a bagpipers knife? It is the wee knife displayed in the top of their kilt hose. The name comes from the Scottish Gaelic sgian-dubh. Pronounced skee-ən-DOO
The primary meaning of the term is Black Knife, refers not to the color but the hidden aspect of the knife. It would be carried under ones’ armpit or out of sight until needed. Scotland was a rough and tumble place in ancient history.
Courtesy and etiquette would demand that when entering the home of a friend, any concealed weapons would be revealed. Thus it follows that the knife would be removed from its hiding place and displayed in the stocking top held securely by the flashes.
The 1995 film Rob Roy staring Liam Neeson and Jessica Lange, has Ms. Lange playing Rob Roy’s wife. In order to keep from being blackmailed, Mrs. Roy cuts a rivals throat.
Quickly, silently as this knife was intended to be used, not very lady like but the end was achieved.
When piper Bill Millin crashed ashore at Sword Beach on D-Day 1944, he was armed only with his pipes and the sgian-dubh, or “black knife”, sheathed inside his kilt-hose on the right side.
Pipers blog 