A tonsure or short haircut makes it harder to grab the other persons hair (speaking of which, I wonder if womens heads were shaved when females fought?) same for the clothing, and also prevents hiding things. This all helps keep the fight even.
Some of the sources mention shaving champions for just this reason. In some cases, duellists were also allowed to grease themselves to make grappling more difficult. The few references I've seen to women in judicial duels don't seem to show or mention hair cutting. Cutting a woman's hair was a form of shaming, so it was probably avoided. Talhoffer shows the woman wearing a tight hood and in Kal she has loose hair. Diebold Schilling shows her wearing an elaborate fifteenth-century head dress. All of these depictions are probably based on a single case, which happened in 1288.
In these earlier specific judicial combats described above, is there information available as to what the outcome was, and what was the aftermath? I'm trying to understand if the duel was more simply to determine guilt (like a trial by ordeal or a baphrobe) or if it was also part of the punishment for the guilty. I gather this varied from place to place, but in records you have seen, was the winner allowed to dispatch his or her opponent or simply to fight until one person won the match after which further punishment would be meted out to the defeated party?
Judicial duels were a form of trial rather than a form of sentencing. If you want to go a step deeper into the abstract theory, some German scholars have debated whether they represented a
beweismittel (a form of proof), or merely an
entscheidungsmittel, a way to reach a decision. Battles usually continued until one combatant gave in. There was no extra credit for doing the executioner's work for him. In practice, I've found that in England and France the fatalities usually occurred in duels between nobles, who were permitted to fight with sharp weapons, while in commoners' battles with clubs or picks, one party usually gave up. Criminal trials usually resulted in the hanging of one of the parties, but "civil" cases were fought by champions and usually did not. The losing champion "lost his law," as they would say at the time. He was not allowed to champion anyone else or testify in court ever again, and he was subject to a number of other legal disabilities.
And finally, my understanding is that judicial combats were normally a way to resolve accusations by one person against another. Are there other circumstances? Someone here a while back (I think it was Roland?) described some records of a convicted felon travelling around England fighting other criminals on behalf of the crown, I assume this would also fit the accuser fighting the accused model. I'm interested in what the other parameters were.
Trial by battle required an accuser to step forward and challenge the defendant. For a while the English royal courts experimented with a system of approvers. An approver was a convicted felon who agreed to accuse his accomplices, and fight them if necessary, in return for being allowed to leave the kingdom. Awhile back I found a reference to an approver who was fighting battles all over England against people he probably didn't know and basically acting like an early crown attorney. That might be the post you're thinking about.
Most of the time, battles that were pledged were never fought. The process worked much the same way a strike works in modern labour law. It was an incentive to negotiate. The idea was to reach a private settlement out of court before the final showdown.