Here the 1905 LDS edition changed whoso to whosoever. This appears to have been a typo made by the 1905 typesetter. The correct whoso was restored in the 1920 LDS edition. The original text of the Book of Mormon has instances of both whosoever and whoso. From Mosiah up to the last part of Helaman, we have instances of only whosoever (including cases of whomsoever); then the text makes a gradual transition from whosoever to whoso from Helaman 13 through Mormon 9. From then on—that is, from Ether to the end of the text and in the small plates of Nephi (at the beginning of the Book of Mormon, but apparently translated last)—we get only whoso. Here in the book of Ether, because of the preceding dominance of whosoever there has been a tendency to replace whoso with whosoever. For two other cases of this error tendency (both by Oliver Cowdery in 𝓟), see under Ether 10:6. For each case of whoso(ever), the critical text will follow the earliest textual sources, thus whoso here in Ether 9:33. In volume 3 of the critical text, I will discuss at some length the possible significance of this transition in word choice from whosoever to whoso. For some preliminary discussion regarding this change in usage, see pages 140–143 of my article “Critical Methodology and the Text of the Book of Mormon”, Review of Books on the Book of Mormon 6/1 (1994): 121–144.
Summary: Maintain the use of whoso in Ether 9:33, the reading of the earliest textual sources.