This is likely to have been made towards the end of the American Revolutionary War (Peace of Paris, 1783) or during the early part of the Napoleonic Wars (starting 1793). This would have been carried by an RN officer or HEIC naval officer, and this example is interesting in having a particularly long (approx 26") blade.

This was introduced in 1859 for the Royal Navy to supply a need for a cutlass and a bayonet in one weapon for the naval rifle of the era, a .577 Enfield cap and ball weapon. This is an A & E Holler example - ie a Solingen blade. There are no UK ordnance marks, so this is almost certainly an American export item.

Regarding the regiment, the Grenadiers had a very specific gorget with multiple pierce work on both wings, the Scots Guards normally had '3rd Guards' engraved on both sides at the tips, therefore, by elimination, this is almost certainly a Coldstream Guards example. The Dighton watercolours of the period appear to confirm this.

These dirks would have been carried by Royal Navy as well as merchant marine officers, even, rather more rarely, by army officers. This classic dirk has a whalebone haft (which, at first glance, might appear to be of walrus ivory, but on closer inspection is definitely whale bone) and iron mounts. The style of hilt, pommel and grip dates it.

This is a senior administrative officer's sword, probably either a surgeon or an apothecary, viz the twin-headed serpent on the guard. The little dolphin head at the end of the knuckle bow by the pommel indicates the naval branch of service. The mounts are ormolu and the grip is ebony.