The engraving on that Krieghoff is nothing like proper Celtic Knott Work as such designs are correctly called. The components are far too widely spaced, where they should be close together. It certainly appears that whoever came up with this design picked up several totally different patterns from some source and lumped them together. There is a major error in the centrepiece engraving in that one belt or strap is shown overlapping three others. This would never happen in Celtic Knot Work they would be interwoven. One mark out of ten from me.
An engraver cannot afford to make a mistake carrying out knot work, as an error stands out like a sore thumb. Most Knot Work designs are at least 1,500 years old in origin and can be found in ancient manuscripts, illuminated religious illustrations such as the Lindisfarne Gospels and Book of Kells, Anglo Saxon Jewellery, gravestones, monuments, tapestries, and weaponry of the time. It was in use for several centuries as decoration or ornamentation.
Sadly like many srt forms it is labour intensive and therefore today very expensive, if done correctly.
Harry
what I had in mind atall atall