Isaiah 49:26 (King James Bible) and they shall be drunken with their own blood as with sweet wine
The King James text here begins the sentence with an and, but the connecting and is missing in the Book of Mormon text. Although this loss of and may be due to scribal error, it is probably best to follow the earliest textual sources (here the original manuscript) since whether or not the and is there makes little difference in the meaning. When this passage is quoted a second time in 2 Nephi 6, the and is there:
There are other cases where the King James and is missing from the corresponding Book of Mormon quotation. Here are a couple of examples from 1 Nephi 20–21:
Although the loss of and in 1 Nephi 21:26 may be an error, it is also possible that its omission is intentional. Sometimes there are differences when an Isaiah passage is multiply quoted in the Book of Mormon. And there is evidence that such differences can be intentional. For an example, see the discussion regarding him versus them under 2 Nephi 6:17–18 (a quotation from Isaiah 49:25–26, which is also quoted here in 1 Nephi 21:25–26).
Summary: Maintain in 1 Nephi 21:26 the clause “they shall be drunken”, which occurs without any connecting and at the beginning of the clause; although the and occurs when this same verse is quoted in 2 Nephi 6:18, its omission here in 1 Nephi 21:26 may be intentional.