For me, the D&C integrates well with the Book of Mormon in many ways, but only when I think of the Book of Mormon in a North American setting. Alma 17 is a good example of why.
I recognize that others find settings outside North America more appealing, and that's fine with me. I just keep wishing Book of Mormon Central would offer people more than one perspective. Other people might also find more affinity with the North American setting, and even those who prefer a different setting presumably want to know why others prefer the North American setting.
The key verse is this: “[The servants] went in unto the king, bearing the arms which had been smitten off by the sword of Ammon, of those who sought to slay him; and they were carried in unto the king for a testimony of the things which they had done”
The KnoWhy gives examples from the Middle-East and Mesoamerica. Those are good examples. War trophies are found throughout history and around the world. The practice is not exclusive to Egyptians or Mayans or Aztecs. Last year archaeologists found a site in France that was several thousand years old and contained a pile of severed arms beneath the remains of a family. Even during World War II, President Roosevelt was presented with " a letter opener made from the forearm of a Japanese soldier. 'This is the sort of gift I like to get,' Pearson quotes FDR saying, although the president did not touch it." Reference here.
The practice of severing arms as war trophies is known around the world, but since I'm focusing on the North American setting for the Book of Mormon, I want to give an example or two from North America.
John Wesley Powell's Annual Report of the Bureau of American Ethnology to the Secretary of the Smithsonian Institution, Volume 9, 1887-88, contains a section on war trophies. On pages 482-3, you can find this explanation:
The use of necklaces of human fingers or of human teeth is to be found in many parts of the world, and besides the fingers themselves, we find the whole arm, or in other cases only the nails. The Cheyenne did not always restrict themselves to fingers; they generally made use of the whole hand, or the arm of the slaughtered enemy. In a colored picture drawn and painted by one of themselves I have a representation of a scalp dance, in which the squaws may be seen dressed in their best, carrying the arms of enemies elevated on high poles and lances.... There is no doubt in my mind that this custom of the Cheyenne of cutting off the arm or hand gave rise to their name in the sign language of the "Slashers," or "Wrist Cutters"...
Kohl assures us that he has been informed that the Ojibwa will frequently cut fingers, arms, and limbs from their enemies and preserve these ghastly relics for use in their dances.
The report also includes an example of the Algonquin who kept the arms of their victims.
The Book of Mormon account does not refer to the use of severed arms in dances, but it does suggest that neither the King nor his subjects seemed shocked at the practice of severing arms. It was Ammon's power that impressed them.
The point is, we can find examples of cultures around the world where severed arms were used as war trophies. But with respect to Book of Mormon geography, we can consult the scriptures to get a more specific indication of where to look.
The Algonquin and Ojibwa were among the tribes visited by Oliver Cowdery, Parley P. Pratt, Ziba Peterson and Peter Whitmer Jr. These tribes were identified in D&C 28, 30 and 32 as Lamanites.