According to an article by William Hamblin and Brent Merrill, there is an interesting incident in the Book of Mormon which involves the staining of swords with blood (see Alma 24:12-15). The Lamanites who had been converted by Ammon refused to take up arms saying, "let us stain our swords no more with the blood of our brethren" (Alma 24:12).
Although today we speak of "stainless steel," in Joseph Smith's day, metals were not generally thought of as becoming stained. Staining was a term that generally applied to wood, cloth, or other substances subject to discoloration. Reference to staining swords with blood is not found in the Bible. Thus, although not impossible, the metaphor of staining metal swords with blood is somewhat unusual. However, if the Nephite sword were the Mesoamerican macuahuitl with a wooden shaft, blood would naturally stain and discolor the wood when an enemy was wounded. Furthermore, if a metal weapon becomes bloody, the blade can be easily wiped clean. Removing a bloodstain from wood is virtually impossible since the blood soaks into the fibers of the wood. Thus the metaphor of the great mercy of God in removing bloodstains from the swords becomes much more powerful and understandable if it refers to wood stained with blood, which only a miracle would remove, rather than if it refers to metal stained with blood, which a piece of cloth would clean. [William J. Hamblin and A. Brent Merrill, "Swords in the Book of Mormon," in Warfare in the Book of Mormon, F.A.R.M.S., p. 342]