sgian dubh vs skean

sgian dubh

noun
  • A small, single-edged knife worn tucked into the hose (stocking) as part of traditional Scottish Highland dress along with the kilt. 

skean

noun
  • A double-edged, leaf-shaped, typically bronze dagger formerly used in Ireland and Scotland. 

How often have the words sgian dubh and skean occurred in a corpus of books? (source: Google Ngram Viewer )