As discussed under Jacob 1:19, the original text had 12 instances of plural mights where modern speakers of English expect the singular might. All but one of these instances of mights were edited to might in the 1920 LDS edition, including here in Ether 15:24. This particular one is interesting in that it is the only one where the preposition is in (“in their mights”). For the 11 other instances of original mights, the preposition is with; there are examples of “with their mights”, “with our mights”, and “with your mights”. Normally, when the preposition is in, the text has the singular might, with three examples of “in their might”:
Nonetheless, the critical text will accept the plural mights here in Ether 15:24 since it is the reading of the earliest extant text. Moreover, there is considerable evidence for mights elsewhere in the original text.
Summary: Restore the original plural mights in Ether 15:24, the reading of the earliest extant text (here the printer’s manuscript).