Just to clarify the remark.
When someone proposes a "way out there" comment or idea, I look at the person posting and the person the post is directed to. If they are reasonably experienced makers, or have expertise in the field being discussed, I rarely make any comment beyond how I might deal with the problem being discussed. However, when the person asking the question does not know enough yet to tell a good answer from a bad one, and the person giving the advice does not appear to have the experience or skill to make that suggestion,.... as moderator - I step in an make a comment. If it is just unrealistic or inaccurate, I merely point out the problem with the suggestion. If it is egregious and would send someone down the wrong path, possibly leading them to where they give up on the project, I am a bit more direct. Over the years I and the long time members here have seen many new members come in and start offering all sorts of advice that they have no experience or real knowledge about. many have offered terrible and dangerous advice. Those type of posts get a quick and direct response.
The OP was a total newbie, and the person giving advice was also. The advisor has no information in his profile or pervious posts that he has any metal working or welding skills. This was enough for me to think a fairly brusk reply was needed.
Remember, all these posts last forever on the internet. Some day a new person will look up some subject and may see this very thread...and try to weld up the scratches on his knife.
Welding up scratches a thin piece of unknown alloy metal with anything but very advanced equipment and skills would be a virtual impossibility. It would require welding fill rods/metal of the same alloy, and still probably show. Welding up a piece of thin metal completely covered in deep scratches would require a full surface build up weld. That would be even more problematic.
If someone doubts this, take a large piece of metal and scar the heck out of it with an angle grinder. Take it to a welding shop and ask what they would charge to restore the surface by welding up the surface to make it scratch free. If they don't laugh at you, the number they quote will make you laugh at them. If you want to go a step farther, go home and try and weld it all up with your shop welder. It will probably end with disaster, but if you finally get it done and grind the surface smooth ( remember, you have no tools but files and sandpaper to do the grinding), see how it looks when done.
The desired finished product Justin wanted in this case would be a simple battle axe profile on a wall hanger. Spending maybe $100 to get it professionally surface welded and many hours smoothing it out would be silly. Trying it at home would be a sure fire failure. Perhaps getting a clean sheet of mild steel from Home Depot or a scarp from a machine shop ( probably free)would be a better method.