Looking at this interesting example, it does seem in the character of a dirk, but of course seems to be a notably ersatz version, but perhaps created by a Scot in military circumstances possibly in WWI period.. The mention of a trench knife brought to mind that a Scot in warfare situation might create a 'trench knife' which was crudely made, but in the character of the traditional dirks of his homeland.
The blade seems either cut down or perhaps even a bayonet blade of the period, with the corrosion under what seems nickel type lamination seen often on late 19th early 20th c steel. The mark may well be the kind of stamped trademark often seen on sheet stock of these times. This kind of marking is seen occurring in kaskara blades of Anglo-Egyptian Sudan c. 1900 of this type steel material.
There are marking scribed into the wood of the hilt appearing to be 4 F ?
suggesting again, perhaps a military unit?
The hilt appears to be of a furniture baluster, a spindle from probably a table leg etc? The pommel is crude but effectively crafted to approximate the types seen on many traditional dirks.
The importance of the dirk to the Scot cannot be underestimated. After the tragedy of Culloden, the Scots were forbidden to possess their faithful swords, nor guns or other weapons.
They were however allowed to keep their dirks for utility purposes, and these replaced in effect the sacred manner that was held in their swords. As a result, many Highland basket hilts had blades cut down into dirks, thus the sanctitude remained in place.
With Scots, their binding oaths were sworn on their dirks, just as they had done on their swords. Before the battle at Culloden, the swords were indeed blessed by the Holy Men.
Despite its crudity, this may well be a dirk to a Scot in war, and in field circumstances, he may have tried to duplicate the kind of weapon sacred to him as a faithful Scot as best he could.
Entirely speculation of course, but viably plausible as deduced.
Romanticized perhaps, but then, it is a hazard of my own ancestry
