Actually, that’s not a katana that’s a sword. There’s a difference in the actual blade of katana has a tilted blade which helps it be more agile and speed, but the sword has a straight blade to make it seem more sharp and strong.
The reason for seasoning the blade from what I was told, Apparently the words for spice and sharpness are the same in Russian so theres a running joke to add spices to the blade to add sharpness