One may wonder here if there isn’t some error involving the conjoined predicate “and praised God”. What we expect is something like “but that they would lay down and perish and praise God even in the very act of perishing under the sword”. The original manuscript is extant here for “and praised God”, but one could conjecture that Oliver Cowdery, the scribe here in 𝓞, might have misinterpreted “and praise God” as “and praised God” since it would be hard to distinguish between the two given the tendency in normal speech to omit the voiced /d/ between the two voiced sounds /z/ and /g/; that is, praised God would tend to be pronounced as if it were praise God, thus leading the scribe to misinterpret praise God /preiz gad/ as praised God /preizd gad/.
Another possibility is that there was a missing subject pronoun they here in Alma 24:23; that is, the original text may have read “and they praised God even in the very act of perishing under the sword”. For evidence that the scribes occasionally deleted the subject pronoun they, see the list of examples under 2 Nephi 27:6.
Of course, if “and they praised God” is a possible reading, then “and praised God”, the earliest reading, is also possible. Basically what we have is the conjoining of two full predicates after the subject they: “would lay down and perish” and “praised God”. In fact, the 1830 typesetter interpreted the text in this way since he placed a comma after perish but not after lay down, thus separating “would lay down and perish” from “and praised God”:
All subsequent editions have continued with this distinguishing use of the comma.
There appear to be no other examples in the text of this kind of conjunctive structure. Even so, since this ellipted reading will work, the critical text will maintain it, although the possibility remains that there is some primitive error here (perhaps the subject pronoun they was lost or an extra d was added to the verb praise).
Summary: Retain in Alma 24:23 the earliest reading (in 𝓞) of “but that they would lay down and perish and praised God even in the very act of perishing under the sword”; this reading will work but may nonetheless be the result of a primitive error in the text.