Brant Gardner notes that after slaying Laban, Nephi dons Laban's clothing (even every whit) and Laban's armor. Nephi specifically says that he does this after severing Laban's head. Clearly there was a significant amount of blood. Wasn't Nephi worried about wearing obviously bloodstained clothes? Hugh Nibley says the following:
Laban was wearing armor, so that the only chance of dispatching him quickly, painlessly, and safely was to cut off his head--the conventional treatment of even petty criminals in the East . . . The donning of the armor was the natural and the shrewd thing for Nephi to do. A number of instances from the last war could be cited to show that a spy in the enemy camp is never so safe as when he is wearing the insignia of a high military official--providing he does not hang around too long, and Nephi had no intention of doing that. No one dares challenge "brig brass" too closely (least of all a grim and hot-tempered Laban): their business is at all times "top secret," and their uniform gives them complete freedom to come and to go unquestioned." (Hugh Nibley, An Approach to the Book of Mormon, pp. 99-100)
[Brant Gardner, "Brant Gardner's Page, "[http://www.highfiber.com/~nahualli/LDStopics/1] Nephi/1 Nephi4.htm, pp. 8-9]