Well they didn't do a very good job......LOL!
I saw a video where some guy who magnet fishes had found numerous knives in rivers and when he was done with them they looked like new..........
The corrosion of the ages is part of the history and provenance of the weapons. Restoration should only be done judiciously and not to make them look new. They aren’t new. The effects of time are part of their story.
If you want to see what these once looked like, the proper way is to duplicate the alloy, and make a replica using techniques as close as possible to the original techniques as can be discerned. . . and documenting the procedure at each step.