I doubt the sword is too heavy, it is the lighter weight.
//The sword used by H.M The Queen at investitures is one of two near identical swords that belonged to The Queen’s father George VI. They were worn by him in his duties as Colonel of the Scots Guards from 1932-37. The sword The Queen uses for investitures is the 'picquet' weight version which is a slightly smaller light dress version worn in court. The Queen lent the other version to the Royal Armouries in the Tower of London in 1952 at the request of the then Master of The Armouries Sir James Mann so that the Royal Armouries could display a sword belonging to each Monarch going back to George II.
Both swords are almost identical, made by the same maker, Edward Smith, etched in bright polished relief with a frosted background with the badges mottoes and battle honours of the Scots Guards and the Cipher of George V. There are two possibilities for the appearance of George V's cypher on the blade: the sword may have been acquired when George VI was Duke of York and Colonel of the Scots Guards, or it belonged to George V and was inherited by his son.//