Skean-dhu

The hasps, which were evidently intended to be secured by padlocks, had lost their fastenings, which were supplied by two skean-dhus—the small dagger of the Highlander—which had been thrust through the iron loops, and kept the casket perfectly water-tight.

Source: wiktionary

It is to be noted that the Dagger does not become a regular feature of knightly accoutrement till the middle of the fourteenth century. [...] A very usual form, both in military and civilian circles, was the Ballok Knife (moderns term it a "kidney dagger"), a type that persisted till the sixteenth century, and whose modern analogue is the Highland dirk (skean-dhu).

Source: wiktionary