The USAF requirements for nidan examination specify two uke for tachi tori, up from one for shodan. What USAF dan examination videos I can find online tend to show multiple uke for buki tori waiting for the examinee to clear and reset before taking their turn to attack, unlike randori, where a greater number of uke means (to various degrees in various examination venues) more to deal with at once.
Was this once an examination element where uke attacked in a coordinated or simultaneous manner, that has since come to be more relaxed? Are there USAF examinations where the uke do attack at once? Or is there another rationale I'm missing for the second tachi tori uke?
Actually, I don't think much of the way the "sword" frequently is used in Aikido. In my opinion, it all too often leads to an almost limitlessly stupid self-overestimation, because in reality you wouldn't have the slightest chance against a good swordsman.
Could the "Randori" with several sword-wielding partners not simply be a holdover from the pre-war and wartime periods impregnated by propaganda ... ?
However, as a pure teaching aid to evoke certain reactions and to explain movement principles in Aikido, the use of a bokken can still be quite useful. However, this should in no way lead to the belief that one can easily disarm anyone as a matter of routine or that one is in any way equal to or even superior to an armed person through one's own knowledge of Aikido.
I don't know your examination system, but I could still imagine that a second partner behind the examinee with his Bokken has the task of forcing the examinee to do a really good Irimi, for example.