Introduction. The main issue solved during the forensic research of cold bladed weapons is the establishment of the object’s belonging to the category of cold weapons. In this case, the measurement of the hardness of the blade is one of the main features, which determine the belonging to the cold weapon. Theoretical analysis. Analyzed compliance of the techniques of establishing the object belonging to a cold weapon to the requirements of metrological norms and rules. It is shown that conducting measurements is an important stage in the production of forensic examinations, and the correctness of the performance of measurements largely affects the correctness of the conclusion. Discussion of results. It is determined that the existing methodology is in contradiction with the existing metrological rules and the ways of overcoming these contradictions are indicated, namely, an algorithm for taking into account accuracy in measuring the hardness of the blade is proposed.