Assentatory

aſſentatory oaths are in caſes of trial by twelve or twenty four appearing as witneſſes, […]

[…] and the civil magistrates not only call you before them to aver the truth therein, but also giving you a good example, cometh before you out of tenderness to their civil trust and duty, to maintain the privileges of parliament; to give a testimony assentatory to their civil rights and privileges; […]

Selden [says] 'All oaths are either promissory or assentatory (assertatory?); the first being that which binds to a future performance of trust; the second that which is taken for the discovery of a past or present truth.

Tacitus and Pliny were without doubt fine orators, even if the former explores the idea of oratory's decline in his Dialogue on Orators and our only example of oratory to survive intact, the latter's Panegyric on Trajan (A.D. 98)[,] strikes moderns as turgid and assentatory.