In his editing for the 1837 edition, Joseph Smith first thought that the relative pronoun which referred to “the Son of our great God”; thus he initially changed the which to who in 𝓟 (a supralinear insertion). But then he realized the which refers to “the blood of the Son of our great God”, so he restored the original which by crossing out the supralinear who and sublinearly inserting which (written as whih, a scribal slip). Elsewhere the text refers to blood being shed at least 45 times, including three other instances referring to the shedding of Christ’s blood:
Of course, the critical text will maintain the original which here in Alma 24:13 no matter whether its reference is to a person or not. For further discussion of the editing of which when it refers to persons, see under which in volume 3.
It should be pointed out here that there are three instances in the current text of bloodshed that could be interpreted as blood shed (that is, as a noun postmodified by a past participle). For discussion of this possibility, see under Mormon 1:12 (there the earliest textual sources read “there was no blood shed” rather than the current LDS reading “there was no bloodshed”).
Summary: Maintain in Alma 24:13 the which that refers to “the blood of the Son of our great God”.