A dagger and robes that shaped the story of Lawrence of Arabia have been saved for the nation with the help of more than £100,000 in grants.

The dagger that belonged to TE Lawrence was sold last year to an overseas buyer but an export bar was imposed on the advice of experts, in the hope that someone would come forward with funding to keep it in the UK.

The National Army Museum has secured the dagger with £78,400 from the National Heritage Memorial Fund.

A second grant from the fund of £35,000 has helped the museum save Arab robes and a headdress, known as a keffiyah, that also once belonged to Lawrence.

Curved steel and silver dagger, presented to TE Lawrence by Sherif Nasir in 1917. Photograph: DCMS/PA

The archaeologist and diplomat was considered one of the most recognisable figures of the first world war due to his involvement in the Middle East and the Arab revolt. He was presented with the curved steel and silver dagger, by Sherif Nasir in 1917 after the Arab forces’ victory against the Turks at Aqaba, Jordan. The scene featured in the 1962 film Lawrence of Arabia.

One of the robes was in a pair given to the mother of Arthur Russell, who enrolled in the tank corps with Lawrence, with instructions to cut them up and make dresses of them.

The kaffiyah was given to the artist Cosmo Clark, who was one of the illustrators for Lawrence’s book, Seven Pillars of Wisdom, after the author sat for a portrait in 1922.

Lawrence said of the Arab dress in which he was always seen: “If you can wear Arab kit when with the tribes, you will acquire their trust and intimacy to a degree impossible in uniform.”

The robes and dagger became part of his mystique and forms the image of him still remembered today.

Culture minister, Matt Hancock, said: “The image of TE Lawrence with his dagger is one of the most iconic of the 20th century.

“It’s fantastic news that thanks to the export bar process this extraordinary piece will now be on display along with his robes and kaffiyah at the National Army Museum for all of the public to enjoy.”

Sir Peter Luff, chairman of the National Heritage Memorial Fund, said: “TE Lawrence was a remarkable man and is an enduring figure in popular culture.

“These items are a vital part of his wartime identity which should not be lost to the nation. That is why the National Heritage Memorial Fund decided to step in to help the National Army Museum to buy them.”

And Dr Peter Johnston, from the National Army Museum, said: “What makes the dagger and robes so significant, and such an important part of British heritage, is the way in which they have featured in the cultural memory and legacy of Lawrence and the Middle East campaign of the first world war.

“The dagger and the robes even became important narrative features at the heart of David Lean’s epic film Lawrence of Arabia, which has shaped and dictated how we in modem Britain, and elsewhere in the world, think of Lawrence of Arabia and Britain’s role in shaping the region.”

The National Army Museum contributed £44,100 to secure the dagger, and £15,000 to acquire the robes.