A neuronphaser.com review.
Arms and Armor was updated during the Castles & Crusades "Three Sisters" (AKA core rulebooks) Kickstarter a couple years back (circa 2016), even though the cover pictured on this product page doesn't show it. What this means is that it is a COMPLETE reference for all mundane armors, helmets, shields, and weapons for the Castles & Crusades system, and with scads of pages of descriptive text noting physical features, measurements, and the history of each piece of gear, this is a useful reference for any OSR game, and probably most any D&D-derived system. There may be some historical inaccuracies -- I didn't note any, but that's not my field at all -- and you may see a lot of items with effectively the same stats, but any duplication in game stats is ignored when you have so much good detail on such a wide variety of items. In other words, the fluff is great, the stats are great, so anywhere you find duplication or superfluous distinctions can be ignored because the whole of the work is fantastic.
Opinion only, but I found a few stats wacky...but literally only a handful. And this opinion is almost strictly formed from having the same general damage notations for said weapons for YEARS. For example, the battle axe in Arms and Armor is rated at 1d6+1 damage and has a throwing range (albeit very short!), and the throwing axe is rated at 1d4 and has a slightly longer throwing range. These numbers are comparable to a shortsword and a dagger, respectively, and the low damage numbers on axes across the board suggests...I dunno. Maybe the writer has a problem with axes? Or maybe they were thinking of some weird critical hit rule that makes axes double their damage more often than swords...? I really don't know, but having played with battle axes dealing 1d8 damage for about 30-ish years just made this stand out, so I personally would take a look at things like that and consider them.
Now, as an off-hand mention, I'm planning to use this book in my Dungeon Crawl Classics games. In comparing the AC bonuses, the damage ratings, gear costs, and all that other stuff to the same in the DCC RPG rulebook, I found most things were a 1:1 match, and the few that weren't were rarely off by much. I quick skim of games like Swords & Wizardry suggests much the same. Point being: if you want to pick this book up and use it in your OSR game of choice, your conversion work is either non-existent or involves flipping a handful of numbers here or there, at most. That's hugely beneficial, and opens up hundreds of weapons, shields, armor, and helmets for any OSR game you care to play.