An 1805 naval officer's sword commissioned by King William IV, known as the Sailor Prince, will star at Bonhams on July 31 in London.

The duke gifted several such swords to distinguished naval officers, himself a captain of the Royal Navy

The sword, which is selling as part of the Antique Arms & Armour sale, holds a £5,000-8,000 ($7,731-12,376) estimate.

Before he became king, William IV held the title of the Duke of Clarence. He earned his nickname after entering the navy at the age of 13 (in 1779), carving out an illustrious career and attaining the rank of captain in 1786.

He was also the best man at Trafalgar hero Lord Nelson's wedding in 1787.

It wasn't until 1790 that William ceased active service in the Royal Navy, but he continued to participate in honorary positions until ascending the throne in 1830.

The sword, made by Prosser, was gifted to Admiral William Carnegie, 7th Earl of Northest, who was the third most senior officer at the Battle of Trafalgar in 1805.

It is one of several such presentation swords that the Duke of Clarence gave to naval officers who had distinguished themselves at sea.

Engraved with the crowned arms of the duke within the belt of the Order of the Garter, it also features a gilt plaque with arms of the recipient, incorporating "Trafalgar".

The sword is being sold complete with its original black leather scabbard.

Paul Fraser Collectibles has an amazing collection of important Nelson memorabilia for sale, including the remarkable Trafalgar Collection.