Peter Citara, 31, pleaded guilty to the theft when he appeared at Berwick Magistrates' Court on Thursday.
Among the valuables found in his apartment was an Indian dagger, Gurkha cookery knife, Afghan muscat and a fighting sword worth £500.
Prosecutor James Long told magistrates the valuables were all packed up ready for shipping back to Citara's homeland in Slovakia.
"It's apparent the defendant had been stealing items over a period of time," said Mr Long. "The items were packaged and it appeared the defendant was going to leave the country.".
The court heard that Chillingham Castle owner Sir Humphry Wakefield first became aware of a problem when the key for a gun cabinet went missing.
After ordering a search of the castle and the staff apartments, 21 valuables were found in the defendant's quarters, including seven from the Great Hall and others from the shop and armour area.
Citara was arrested on November 6 and appeared before magistrates in Berwick on November 11 when he was remanded in custody for reports to be prepared.
He appeared before the court again on Thursday when it emerged he had worked for Sir Humphry for three years, initially on the estate and farm and then in the castle as a handyman and head of security.
Sir Humphry revealed in a statement that he had noticed things going missing over a period of time, particularly two rings belonging to his wife, and the missing key to his gun cabinet had brought matters to a head.
"This is a total betrayal of my trust," said Sir Humphry. "It was his job to protect these valuables."
In mitigation, Stephen Davies pointed out that all the items in question had been recovered without even leaving the castle.
He said: "It's an unusual case in that the items were not only recovered, they did not even leave Chillingham Castle, albeit they were found in a different room."
He admitted the valuables were stored in crates ready to be moved but this was because he was moving to a different apartment within the castle.
"No decision had been made by him to return to Slovakia," added Mr Davies. "He is here in the UK because the money he can earn is better than he could make back home.
"He told police he might take the property back to Slovakia but the fact of the matter is that he did not get that far."
He revealed that Citara, a martial arts and weaponry enthusiast, was seeking new employment in Aberdeen.
In a pre-sentence report, probation officer Nicola Bridgeman admitted magistrates faced a difficult decision but said Citara appeared to be a 'low risk'.
She said: "He can't give a reasonable excuse as to why he had the goods in his possession but he is very aware of the breach of trust he has caused."
Magistrates imposed a sentence of six weeks custody suspended for two years, along with a £70 fine and an exclusion order to stay out of the grounds and buildings of Chillingham Castle.