Unknown Insignia

I have a sterling silver mustard? pot and teaspoon that has an insignia that is unknown to me. The teaspoon has Edinburgh marks, the maker’s initials P H, and a date letter of the 1830’s. The pot has Sheffield marks, made by Henry Wilkinson and Co. in 1837. Each item has an insignia that comprises a ribbon banner with the latin words DISCITE JUSTITIAM above a Lady Justice. My question - to what organisation, society, group etc does it belong to?

“Discite justitiam” (learn justice) is the motto of a Scottish branch of the Nisbet family, but a description of their arms (from Fairbairn’s Crests, 1883) does not match your spoon: “out of a cloud, in fess, a dexter hand holding a balance and scales, all proper”, although it has the same idea of the scales of justice. I note that the spoon is dated 1839 to go with your 1837 mustard so it may be an earlier branch of the family.