The order will extend the closely watched trial, which is set to resume in November with Siti as its first witness.
Separately, Doan's lawyer, Hisyam Teh Poh Teik, said the defence was unhappy with the ruling but accepted it. Both women pleaded not guilty. "The court wants to hear their version".
In Vietnam, Huong's father, Doan Van Thanh, said he hoped the court would be fair.
If so, the trial will continue with the court hearing the women's defence.
Pyongyang has denied accusations by South Korean and U.S. officials that Kim Jong-un's regime was behind the killing.
Azmi said he "cannot rule out that this could be a political assassination", but found no concrete evidence of one.
The women are accused of colluding with four North Korean suspects who fled the country the same morning Kim was killed. The defense has argued the real culprits are the four North Korean suspects and have pointed to an embassy employee who helped arrange their travel as evidence of embassy involvement.
Prosecutors allege that Doan's behavior after the incident - security footage shows her rushing to the washroom with her hands held away from her body - indicates that she was, in fact, aware of handling a risky substance.
Prosecutors say Aisyah and Huong knew what they were doing and meant to kill Kim, who had been living in self-imposed exile in the Chinese enclave of Macau for more than a decade after falling from grace in his home country.
Killed in Bridge Collapse in Genoa
Opened in 1967, the bridge is part of the A10 motorway connecting Genoa to France and is named after designer Riccardo Morandi. Italy's national fire service said on Twitter that 200 of its emergency workers were involved in the rescue effort.
Siti Aisyah, 26, and Doan, 29, were charged along with four others still at large, with the murder of Kim Chol, 45, at the klia2 departure hall at am on Feb 13 of a year ago. The prosecution also maintained the argument that the pair were trained to commit the crime.
In her cautioned statement, Doan claimed she was told to carry out a "prank" on Jong Nam by four North Koreans. Pyongyang hits back, expelling Malaysia s envoy.
At the end of the month, Malaysia s then-Prime Minister Najib Razak announces an agreement has been reached to return the body to North Korea.
Malaysia arrested North Korean citizen Ri Jong Chol in connection with the murder.
North Korea pours scorn on what it calls "absurd" claims that VX was used, saying South Korea and the United States are mounting a smear campaign against it.
But the trial of Kim's alleged murderers has taken place against the backdrop of rapprochement between Pyongyang and Washington and a charm offensive by Kim Jong Un, who has embraced the role of a globe-trotting statesman.
Besides the Rodong Sinmun, the North's external propaganda media outlets have recently stepped up calls on the South to choose between sanctions and relationship improvement.
Kim had been living in exile with his family in the Chinese territory of Macau. He was believed to be in possession of large amounts of cash.
The message was delivered to the North's leader as Putin congratulated North Korea on the 73rd anniversary of Korea's liberation from Japan's 1910-45 colonial rule, according to the Korean Central News Agency (KCNA).