Tinyroots Choji Oil Tool Cleaning Kit, Simply Wipe the Knife Oil on to Restore Your Sword, Knives, Bonsai Tools, Includes Rust Eraser and Lint Free Cloth

For any traces of rust, I use Tinyroots Choji Oil, which also comes with a cleaning cloth and rust eraser. So far, it's worked so far for my katanas, but don't know regarding longswords or any European sword. Below is the link to said product: https://a.co/d/01sWigF4

Lots of methods to do this, but for me, I use Tinyroots brand Choji Oil, which I have linked in this comment, as well, to prevent any rusting on my katanas. In addition, it also comes with a "rust eraser" of sorts that can get rid of light rusting on blades. I also always make sure to wipe and re-oil my katanas at least 1-2 times a month, if I'm able. Tinyroots Choji Oil Tool Cleaning... https://www.amazon.com/dp/B007P3XUIE?ref=ppx_pop_mob_ap_share Hope this helps.