An “incredibly rare” piece of Roman armour from the second century has been reconstructed from dozens of fragments.

The brass arm guard, owned by National Museums Scotland, will be seen for the first time in its entirety in nearly 2,000 years when it goes on loan next month to the British Museum in London for its exhibition, Legion: Life In The Roman Army.

Conservators spent weeks reconstructing the arm guard, which is the most intact example of its kind and is one of only three known from the whole Roman Empire.

The armour was previously in more than 100 pieces when it was discovered at the Trimontium fort site near Melrose, Scottish Borders, in 1906.

The fragments have been in National Museums Scotland’s collection for more than a century, with the upper section previously on display for 25 years.

Now that all fragments have been reassembled, the arm guard will go on permanent display in the National Museum of Scotland in Edinburgh after the British Museum exhibition ends.

Fraser Hunter, principal curator of prehistoric and roman archaeology at National Museums Scotland, said: “This is an incredibly rare object, and it’s great that this exhibition gave us the opportunity to rebuild it.

“The transformation is striking. Now that it’s been reconstructed, you can picture the legionary who once wore it.

“It was both protection and status symbol – brass was expensive and would have gleamed like gold on his sword arm.

“It offers a vivid connection to this important period when Scotland sat on the Roman Empire’s northern frontier.”

Bethan Bryan, assistant artefact conservator at National Museums Scotland, added: “It’s been a privilege to work on such an extraordinary piece of Scotland’s history.

“Approaching this ancient jigsaw puzzle required careful consideration and it was important to make sure we could display the piece in a manner as near as possible to how it would have looked 2,000 years ago.

“I’m thrilled that it can now be seen by audiences in a new light and has been preserved for generations to enjoy.”

Richard Abdy, curator of roman and iron age coins at the British Museum, said hosting the exhibition is a “splendid privilege”.

He said: “The flexible arm guard is an iconic piece of equipment for Roman gladiators, so it is unusual to see it as a sword arm protection for Roman soldiers too.

“Its display, posed with classic legionary segmental body armour, is stunning. The latter is also possibly derived from gladiator kit and we even think that the training regime for the amphitheatre originally inspired combat training of the professionalising Roman army.

“The image of Roman soldiers and gladiators appropriately unite in one artefact – two characteristic strands of the dark side of Roman civilisation that have long fascinated public imagination.”