Based on the excellent reputations of the Mora knives that I had frequently read here on THR, I bought two of them about a year ago - one carbon steel blade, and one stainless steel blade. I had read (briefly, not in any tremendous detail) pros and cons about each steel type and figured I’d like to try both. At any rate, I threw both in my BOB and basically forgot about em for the better part of the year. To make a long story short, I had the opportunity to use the knives to field dress, skin, and butcher up a whitetail buck about a week ago. Prior to that, both blades were brand new and had never been used to cut anything. Additionally, I had visually inspected both and they both had the appearance of knives that had just been opened from the original package in the past few moments. After the work on the deer (about three-ish hours, it was my first time leading the job), I took both knives in the kitchen and washed them thoroughly with dish soap and water the same way I would with any of my dishes. I noticed the carbon steel blade had a very unique “wear” on it at this point - literally immediately after washing, for lack of better way to put it. The same knife was used and washed, again, after a similar but smaller job a few days ago. The following three pictures are the two knives tonight. Blue is the stainless, orange is the carbon steel. Is the blade damaged, or is this normal? Do I need to oil this blade? If so what type? Gun oil? Will this “wear” or “patina” or whatever it is damage the blade, or is it purely cosmetic? Both knives performed excellently, FWIW. Both need to be sharpened up, but other than that I am extremely pleased. Thanks for the help. P.S. I know it looks like the orange/carbon steel knife has some gunk at the base of the blade where it meets the handle, but I assure you there is nothing there that can be washed or scraped away. It’s just discoloration on the steel.