Hi Gaoler,
This is something I've considered for some time, as there would appear to be a gap in our knowledge with regard to tools used for clearing and chopping of undergrowth. The reason for this is simple; that historical interest has, until recently, been placed almost exclusively on the doings of the rich and powerful, palaces, castles, battlefields, powerful individuals, etc; while ordinary people and how they lived has been largely ignored.
The origin of the word "dirk" is unclear, but there seems to be a popular belief that it originates in the C17th, and as a loan-word from Danish or Norse. Not only are almost all other Danish/Norse loan-words in our language of far older use, but the word itself is used prior to that date, as in 15th and 16th century documents, charge sheets, inventories, etc.
It may be of passing interest to some, that I suspect the influence of Bronze Age toolmaking to have survived well beyond the Iron Age in the form of design. The general design of the bolster of the Ballock/Ballick dirk is greatly reminiscent of Bronze Age design, and may arguably be compared to elements of La Tene style and its later influence seen in British metal work.
By the C18th the word is in common usage and by the C19th, is being bandied around to describe anything sharp, pointy and too handy. In 1810, the writer James Hogg, The Ettrick Shepherd, was invited to a society dinner by the Edinburgh "Glitteratti". Hogg, who had never seen a fork before then, made quite an impression when he "drew a dirk at the table and frightened the ladies".
(There's some evidence that it wasn't just a dirk he drew out and impressed the ladies with, and it didn't take long before the resentment of the "Glitteratti" were acting to exclude this simple shepherd and literary genius from the printer's shop. They began referring to Hogg as "The Pig", to which Hogg retorted that "It's gei quair folk that canna tell a pig frae a sheep!" Well, nobody remembers their names!)
By the C19th, the word "dirk" has also been hijacked by the military and is being used as a term for any dagger-like implement from a naval officer's dirk to a ceremonial dirk, as the British military proudly took possession of terms from a culture they had effectively exterminated only a short time before. The one sense of the original meaning of the "dirk" that remains is that it was a tool for the sole purpose of killing!
To go back to my original statement, that there is a gap in our knowledge of bladed tools used in Scotland, although style and design being far from unitary in greatly diverse Scottish cultures. We know from Pictish stones and various rock carving that the hatchet was probably a common tool (see the Rhynie Man). Axes were obviously common, although the main evidence for this is the vast array of styles of war axes, from the halberd to the Lochaber axe; the style of war axe varying from region to region, and we know the favoured modus operandi of Robert the Bruce was as an axe-man!
I have seen on numerous occasions, a tool resembling a cross between a sickle and a bill-hook, being sturdier than a sickle and less heavy than a bill-hook. I have only seen these tools in Fife or Clackmannanshire (which is merely Fife under occupation), in small local museums or exhibitions of farming implements. Many such tools were probably locally produced by blacksmiths, although there were areas well known for the production of knife and cutting implements, such as Kilmarnock, which came to specialise in mass production of knives and blades but seems to have been known as a manufacture centre as early as about C15th.
Here is a link to a site which I'll admit not having looked at properly, although seemingly of interest concentrated around the late C19th at earliest.
Scottish Transport & Industry Collections Knowledge network; STICK (they obviously struggled with the extra "n")
http://www.stickssn.org/site/pages/projects/old-tools-new-uses/otnu-master-catalogue.php
There are links to various tool categories at the foot of the page, which in turn provide a list of museums with tool collections. I have found museum staff, even Curators, to be extremely approachable and helpful, and prepared to answer enquiries to the best of their ability.
Hope it's of some use, and certainly a topic I will have to look at more closely.
Cheers,
Pango.
and yes, women do wear them with their arisaids 
Lot of us wearing them again 
I think the arisaid is beautiful, and much like an Indian lady with her sari and the veil over her hair, it must have looked attractive to those repressed folks whose women folks were all tied into corsets with their hair all pinned and powdered so tightly. Just jealous 
