Scale= from old North French (see escale),another possible orgin is Old Highlands German
(see scala).Courtesy an ancient World Book Encyclopedia Dictionary.Take your pick the word has its roots in one.To substantiate the French usage,most of our knife nomenclature of today is of French orgin:ricasso/choil,sabatier/a very early French cutlery,knife pattern dating back several 100 years.The Germany's were very early knife makers as well.As some of the Solingen pattern exist today which date back to merely an area of Germany before a town bearing that existed.The town existed in 1790 to early 1800 so the area before that.
Scales has many definations,as in those of fish and flakes on butterflies wings.Slabs, used for the same term has many definations too.Also planks was used for the same term.These are English terms and date back nearly as far.So,the word has been around along time,take your pick of the orgins.DM