Evidential identification of weapons can be completed by an officer. An expert witness is not required.
There is no requirement for an expert witness to make an identification of a weapon prohibited under legislation. It has been agreed with the CPS that the process of identifying a weapon (typically measuring, commenting on points, holes etc). can be carried out by any individual.
The Knife Crime Coordination Centre have a cadre of individuals who are experienced in identifying a variety of weapons and are happy to assist and advise.
Attached to this article are a number of template proformas that can be adopted for weapon identification.