Hi Chris
Officially you are right. There are official limitations. The main security concerns on trains are related to the comfort and safety of other passengers. Practically no one will bother you about a personal letherman packed deep in your backpack. On flights the security measures are aimed to prevent hijacking of the aircraft, therefore you can not board with a knife. This is not the case on trains.
I will take the opportunity to share with you a Mongolian legend related to knives.
"Ten Thousand Knives" Statue
The story of the "Ten Thousand Knives" statue, as told by Monk Konchog Norbu, emphasizes Danzan Ravjaa's charisma and leadership (a legendary Gobi monk 1803-1856). Norbu explains that the Khamariin Khiid, Danzan Ravjaa's home monastery in the Gobi desert, was known for it's harmonious community. The unexpected stabbing to death of a Chinese person in 1825 following a dispute, came as a great surprise and shattered the peaceful community.
Danzan Ravjaa grasped the opportunity. He asked that all knives that might be used as weapons from the surrounding area to be brought to him. The response was outstanding - 10,000 knives were brought to the Monastery doorstep.
Danzan Ravjaa had all the knives melted down and forged into an exquisite statue of Guru Rinpoche, founder of the Nyingma lineage, known as the Red Hat school of Buddhist thought. Although Khamariin Khiid was associated with the Tibetan Red Hat, Danzan Ravjaa built temples to honor both the Red Hat and the rivalry Yellow Hat lineage, resulting in conflict with the spiritual hierarchy of his time.
Once displayed, the statue became an object of pilgrimage known as the Statue of "Ten Thousand Knives" and peace prevailed at Khamariin Khiid for the rest of Danzan Ravjaa's life.
Photo - Ten Thousand Knives Statue
Source - Treasure hunt
Have a safe trip on the train.
Dan