1. I may be interpreting it wrong, but patch notes on 20 October update (
https://steamdb.info/patchnotes/2217263/) show:
Horseless Headless Horsemann's Headtaker Removed attribute item_class tf_weapon_sword
Eyelander Removed attribute item_class tf_weapon_sword
Nessie's Nine Iron Removed attribute item_class tf_weapon_sword
2. Viewing items_game.txt show that weapons that used to show "item_class tf_weapon_sword" now do not show item_class at all (such as Persian Persuader). Instead, it shows up as "prefab weapon_sword"
3. I use the Uber Upgrades plugin which uses the weapon class to determine upgrade eligibility, and just recently noticed that I can't upgrade swords. I'm assuming this changed in the Inferno update, but I could be wrong.