There are extensive documentations on how at least pre-modern European fights to the death went!
It’s just a pain to get them.
Most are church or legal records.
Church because that’s where all the records were kept in many cases
Legal because judicial dueling was a very significant part of jurisprudence in some times and places.
While the particulars of how weapons are used on the field are largely lost aside from poetic description or Roman manuals…
The inventories of arms are not lost!
Further, there are legal records regarding how a levy, fyrd, or men at arms were expected to be equiped in addition to their numbers in fulfilling feudal obligations.
Mind you, the individual soldier or militia person may bring more than the mandatory kit, but they often had at least the minimum.
As far as this one knows, the Caledonians had a deep love of shields. With the occasional spiked variety seeing use. Single central spike, not like the puffer fish helms in the Pacific. A shield is almost without exception a superior option to a dagger. Especially when paired with a basket hilt sword. Mind you, the claymore was more a weapon of the age of Pike and Powder than the Middle Ages, but that’s getting into left field.
This one can go rummaging for museum references, but it’s been a few years since I’ve had those put together for a class.
Edit: Easiest way to get to the documents, or at least to look at them is to have credentials as a documentary Journalist, good references from other museums (easy enough to get if one has time to do volunteer work), or a recommendation from and education establishment.
In regards to having it in game.
It is as anti-practical as rushing into battle in a fur banana hammock…
But rule of cool has to take prime placement in this regard. If the character can drink sewage with no adverse health issues, perhaps they likewise possess the near super human ability to make dual wielding viable on par with longarm or sword and board fighting styles.