Beneficiarius was a functionary soldier, not a unit in the Roman army. This soldier was the equivalent of our officer for special assignments. He dealt with administrative and legal matters, acting on behalf of the commander – a legion of the legion or military governor, e.g. of the province, to whom he was directly subordinate and with whom he consulted all important decisions. He was also involved in logistics or was responsible for the Roman military police. So it was an elite and important function.
Such a soldier, while performing his duties, was exempted from typical activities performed by all legionaries. The spear he wore was an attribute symbol (signum) – similar to the lictors) – of his power and competence. They also coordinated the work of military intelligence, and dealt with the Empire’s estates and mines (depending on the period), under the responsibility of the provincial governors. They generally dealt with administrative matters related to the Roman army.