Oliver Cowdery initially wrote in 𝓟 “with all manner of weapons of war”, probably because he expected weapons of war rather than weapons alone. Oliver corrected his error by crossing out the prepositional phrase of war and supralinearly inserting which. There is no change in the level of ink flow for the correction. As noted in the discussion under Mosiah 9:3, in this part of the printer’s manuscript, Oliver frequently wrote (at least initially) what he expected rather than what his copy-text (the original manuscript) read.
Elsewhere the text has 46 occurrences of “weapons of war” but only 4 instances where weapons occurs without any prepositional postmodification. In a nearby passage, we have instances of both cases:
In Mosiah 9:16, the original manuscript undoubtedly read simply as “all manner of weapons”— that is, without the expected of war. There would have been no motivation for Oliver Cowdery to have crossed out of war except that the original manuscript read without it. This specific reading without of war (that is, “all manner of weapons”) is unique to the text and differs from six occurrences of “all manner of weapons of war” elsewhere in the text.
Summary: Maintain in Mosiah 9:16 the corrected reading in 𝓟 which lacks the normally expected prepositional postmodifier of war: “and with all manner of weapons which we could invent”).