it appears that many who are troubled by the events in the original post are missing the forest because they are totally occupied with the mainicured garden.  Stated otherwise, they are trying to apply rules from one carefully defined structure (Western Judeo-Christian human culture) to an entirely different and much less constrained structure ( The (Unseelie) Winter faerie culture, as defined by Jim based on historical references)

Why in the world would the rules be even vaguely similar?  Because they used to be humans (some of them)?  what if none of them were Western Humans, what if they were from the Assyrian empire ( look it up, arguably the longest lasting, and most viciously cruel human society that ever existed, over 1000 years)?  what if they were from the Mongolian empire of Genghis Kahn, where there were many laws, but the punishment for almost all of them was death?

What if they just followed the one law all living creatures do, that if it can kill you, you leave it alone, unless you are forced into a confrontation?

in a society defined by never trust anyone, never turn your back on anyone, might makes right and the strong can have whatever they can take (well defined in the chapters preceding the party), and the only real rule is to not upset those who can kill you (say, Mab), then you define your place in that hierarchy by killing.  Its that simple.  As many as you need to, or want to, or are forced to not exceed.

you can also be defined by not being able to kill but being protected by another who can (see "marriage" in less well regulated societies than the ones in the modern West)

The world we live in and the one Jim writes in are defined by the aggressive use of force, those who can use it, and their victims or dependents who will not or cannot.

Nemesis's power to influence people is limited. It can't bend them into something totally opposite of what they were. From what we've seen of it so far, it removes some of your natural restrictions, gives you "free" will, and nudges you down roads where your desire or ambition is already leading, but common sense or the order of things keeps you from pursuing.

^^ This
But...
Cat Sith, there was total "Borg" Like domination of the Cat Sith.
Others though, I entirely agree.  Victor Sells all the way through to the porn star death cult, they were pursuing their own aims, but the infection allowed or spurred them on to taking the efforts to the extreme

LOL, it was from that Dragon Magazine article that I was first introduced to her!  It was the tesseract her hut was internally that really intrigued me

The issue I keep running into is that 1064-1066 was during the "Historical Cycle" of Irish mythology and most of the documentation I have found deals with the disgrace and death of Donnchad mac Briain and the power grab by his successor, which effectively ended the power of the High King in Ireland.  Not finding references to Faerie, though there is a lot in the Ulster and Fenian cycles, but they were around the birth of Christ through the 400's, outside of the date range we were given.  I looked through them anyway,trying to find any woman wielding a staff at all, but I did not have the gumption to go over the translated texts, just looked at synopsis.
There seems to be an association with "Anann" an aspect of a tripartite goddess of death destructions and such, called "Morrigan" who has a few websites devoted to her current worship (?!?)