Guilty Gear XX #Reload - The Midnight Carnival.
It has an official PC port, but unfortunately, no online play although you can search for an unofficial third party patch to do that. Its one of the best and underrated 2D fighting games out there with deep technical play and weapons.
Thats probably about the most modern fighting game I can think of for the PC. If you want to step back to like way over a decade ago, there are PC ports of a few Street Fighter games (Alpha 2), or Sega's Virtua Fighter 1 and 2.
Otherwise last resort is to go to emulators and ROMs or search deep on the interweb for some Japanese doujinshi games.