The shoes and a 'gamchha' or stole worn by accused, Naresh Kumar, at the time of the killing have also been found from his house in Palwal, police said.
"We have recovered the knife used in stabbing," Haryana, Government Railway Police SP Kamaldeep Goyal said.
Junaid Khan, 17 was stabbed to death onboard the Mathura-bound train when he and his brothers were returning home to Khandawli village after shopping for Eid in Delhi. His body was dumped close to Asaoti village in Faridabad district.
The 30-year-old accused was arrested from Maharashtra's Dhule district on July 8, about a fortnight after the June 22 incident which had triggered a nationwide outrage.
During investigation, Naresh Kumar told police that he had bought the knife from Delhi on the same day. After the crime, he put it in a bag and dumped it in a pond in Jatola village, police said.
The accused works as a security guard in a Delhi firm.
Superintendent of police Kamaldeep Goyal said police was yet to recover the T-shirt which he was wearing at the time of incident. He will be taken to Maharashtra for its recovery.
The knife and other items recovered by the police would be sent to a forensic lab in Bhondsi in Gurugram for examination, police said.
Mr Goyal said accused was sent to police remand for five days by a court here yesterday.
Naresh Kumar, a prime accused in the killing of Junaid, had "confessed" to having stabbed the victim.
Junaid Khan was stabbed to death while his brothers, Hashim and Sakir, were injured by a mob which also allegedly hurled communal slurs against them.
His brothers had claimed the attackers had taunted and repeatedly called them "anti-nationals" and "beef eaters".
A reward of Rs two lakh had been announced for information on identity of those involved in the killing.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)