I've been trying to find actual documentation on this particular sgain dubh actually being issued to the Highland Regiments, but I haven't stumbled on anything so far.

If it is based on the Swiss Army Knife, it certainly wouldn't have been around in the Crimea, since that war was in 1854, and the Swiss Army Knife wasn't issued to the Swiss Army until the early 1890's as a multi-tool for the soldier's rifles.

Cheers,

Todd