One-on-one combat between biont or other sapients under the supervision of higher level transapients.
Many sapient-friendly SI:>>1 (higher level transapients and low level archai) use duels to solve the obvious problem: if bionts and other sapients are allowed freedom, does it include the right to fight and start a war among themselves? And if they war, how to avoid sophont suffering and a costly disturbance to whatever purposes the SI:>>1 uses sapients for (infrastructure building, sociological experiment, entertainment etc.)?
In a ritualized combat, the SI:>>1 shows emself and asks the warring parties to choose one representative. Then, a lengthy protocol establishes what forms of combat and weapons are allowed. These range from literally hand-to-hand to warship-to-warship combat. The combatants fight under the supervision of judges of both parties and the archai. The winning side wins the war. Traditionally, the choice of whether the combatants fight to the death is left to the warriors themselves.
Ritualized combats are more common in lower technology areas and in sub-classes of society like corporations etc. The visible role of the SI:>>1 is usually limited to that of a final arbiter and setting the protocol rules (which might actually determine the outcome).
It is important to understand, that duels are set by the SI:>>1 to avoid war, not to wage it. Therefore, the SI:>>1 usually allows a long protocol for choosing the judging committee, choosing weapons, a complicated duel ritual and plenty of opportunities for the two parties to get to know each other, emotions to calm down and possibly to work out a compromise.
Ritual duels are also a staple of the entertainment channels.