Correction of Quotes from Huxford by Spiral

[Berkley]

Each man to retain and wear his kookrey in a leather waistbelt of the pattern which has been approved.

A standard rule of English construction (a subject well known and understood in 1815 - perhaps more so than is the case today) is that an adjectavial clause ("of the pattern which has been approved") always follows the person, place or thing it describes ("a leather waistbelt"), usually immediately.

In other words kukri were made to an approved pattern

Misreading an accurately quoted primary source, through lack of understanding of basic principles of grammar, can cause one to draw erroneous conclusions. Uniforms (including waistbelts) of the 1st Nasiri ( AKA Nusseree) Battalion were indeed of a prescribed pattern: LINK. Unless there is evidence of a similar approved pattern for the kukris, I believe you have misread the quoted passage, and drawn an erroneous conclusion as a result.