So me and my buddy are currently working on a story that takes place on a different earth-like planet similar to when carboniferous life like the Meganeura dragonfly inhabit the landscape. A few differences is that the 'Humans' that evolved on this planet to unaffected by the high oxygen in the atmosphere. (33% of atmosphere to be specific). The era we're worldbuilding takes place in there medieval era.
When I was doing some research on the different iron alloys. I've read that metals like iron would naturally degrade into rust over time due to binding of oxygen in the air. Natural elements like Water & especially salt water would degrade iron much more quickly. I did some research on things like Rust-resistant alloys & Galvanization. But The only problem with those 2 is these were modern methods that likely required the discovery of electricity to make these alloys.
Question: Would an atmosphere with 33% oxygen significantly alter our world's historical uses of iron for tools, structures, armor and weapons?