delighting in lightning

you seem like the right person to ask about jewish knights and judaism in general in arthurian legend

Hello! Apologies for how long it has taken me to respond to this! Throughout the Middle Ages and the early modern period, there were a number of Arthurian texts written by and for Jewish people in Jewish languages. The one I specialize in is an Old Yiddish text called Vidvilt, which is part of the Fair Unknown tradition and based off an earlier German text called Wigalois. This text was super popular in the Yiddish-speaking world for about three centuries or so and was reworked and reprinted a number of times. I already discussed some of those adaptations a while ago in response to this ask.

Predating Vidvilt, there was a Hebrew Arthurian text written in the 13th century which is now commonly known as Melekh Artus. This was based on Old French sources and tells the story of Arthur's birth and Lancelot's affair with Guinevere before breaking off unfinished. The most common edition of the text used today is the one by Curt Leviant, though I just read a fascinating article in the latest issue of the Journal of the International Arthurian Society calling into question some of his transcription choices and the conclusions he draws in his analysis of the text.

I also recently read that a fragment of an Arthurian text in Judeo-Catalan was recently discovered, but I'm afraid I don't know much about it as yet other than that it's apparently a late medieval adaptation of Jaufre.

Chivalric romances of both Christian and Jewish origin were extremely popular among medieval and early modern Jews in general. There were a number of non-Arthurian knight stories that were very popular as well; for example, the most famous and influential work of early Yiddish literature was a chivalric epic called Bovo d'Antona, and a survey I read of the literature in Jewish households in early modern Italy shows that the most popular non-religious work among Jews at that time was Orlando Furioso.

It is worth noting that, even though some of these texts were written by and for Jews, that doesn't necessarily mean that the characters in them were Jewish. Jewish writers generally tended to modify their Christian source materials by gliding over or obscuring references to religion, rather than depicting Judaism directly (the reasons for this are complex and could constitute a whole paper, so I won't get into it here). That being said, medieval Jewish knights did exist in real life, too! There are a few medieval historians who do research into exactly when, where, and under what circumstances Jews were allowed to bear arms, but it definitely wasn't exclusively a literary thing.