Here the word "hand" represents authority and possession. Abijah is claiming that only the descendants of David have the rightful authority to rule Yahweh's kingdom. This can be stated in active form. Alternate translation: "that the descendants of David hold within their hand" or "which only the descendants of David have the authority to rule" (See: [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-activepassive]])
It might be best to translate so that the reader understands that Jeroboam had others make the golden calves. Alternate translation: "the golden calves that Jeroboam had his craftsmen make" (See: [[rc://en/ta/man/jit/figs-metonymy]])