Here in the original manuscript, Oliver Cowdery wrote “& as it brake by the hilt”. Later, when he copied the text from 𝓞 into 𝓟, Oliver also wrote “& as it brake by the hilt” in 𝓟. At that time, he seems to have noticed that the as didn’t make much sense given that this short as-clause is followed by a completely independent and semantically unrelated conjoined clause (“and he also smote Zerahemnah”). Even though 𝓞 itself read as, Oliver decided to remove it from both manuscripts, yet his correction in both cases was defective. In the printer’s manuscript, he crossed out the preceding ampersand as well as the as; in the original manuscript, he crossed out the following it as well as the as. The 1830 typesetter, on the other hand, ended up with the correct and it, perhaps as a result of proofing the 1830 sheet against 𝓞 (see the discussion under Alma 42:31). The it is required; and without the and, the text reads awkwardly (“behold one of Moroni’s soldiers smote it even to the earth / it brake by the hilt”). The critical text will accept the 1830 reading here (“and it brake by the hilt”), which was apparently what Oliver intended to correct the text to in both manuscripts. The extra as was probably prompted by the occurrence of as earlier in the passage (“but as he raised his sword”).
One other aspect of 𝓞 shows that the crossout of as it took place later. Oliver Cowdery spilled several ink drops on 𝓞 when he made this crossout in 𝓞, and one of the drops fell on text that had already been written on the opposing page of the spread. The crossed-out as it is next to the gutter on the left-side page of the spread (the verso) while an extra drop of ink is next to the gutter on the corresponding right-side page of the spread (the recto) and partially covers the initial word of the preface to Alma 45 (namely, the upper part of the Th that begins “The account of the People of Nephi”).
Summary: Accept in Alma 44:12 the 1830 typesetter’s interpretation, “and it brake by the hilt”, of Oliver Cowdery’s improperly corrected readings in 𝓞 and 𝓟 (respectively “and brake by the hilt” and “it brake by the hilt”); the inclusion of as in this clause (“and as it brake by the hilt”), found originally in both manuscripts, seems to be an error caused by the use of as in the preceding text (“but as he raised his sword”).