Maybe I didn't understand well enough what I was purchasing when I grabbed this, but from the introduction I thought it would be a treatise on weapons, dungeon features, terminology, and the historical Medieval sources of many of the elements we see in TTRPGs:
"Where other people were inspired by the fiction in Appendix N, I was drawn to the strange (but real) vocabulary that he used. Weapons I’d never heard of before. Dungeon features that I had to look up to know what they were. Terms for characters of various classes and levels that were drawn from actual occupations and designations that existed in the past."
What this seems to be, however, is a compilation of texts on various topics from the public domain. A lot of the articles are lifted wholesale from historian Henry Osborn Taylor, among others. There's no context whatsoever in terms of how these historical elements factor into the classic D&D setting or tabletop games of today and many of the articles focus on Latin prose and poetry, often without translation. I'm perplexed by this release.