Guest,

"I searched for it, but no source that I've found seems to know about
the origin of the kilt. They also wear some sort of a sash around
their shoulers.
I guess they just couldn't sew very well to make pants at the time,
so it became traditional..."
The little kilt (I won't insult gaelic spekers with my appalling attempts at the language) - the kilt we know today, owes it's origin, in part to the 'great kilt' or belted plaid . This was a single length of cloth held at the waist by a belt, half as a kilt and the other over the shoulder. This served the highlander as both nether and upper garment, the upper section being drawn around like wearing a blanket or shawl. The plaid also served as a highlander'sshelter, blanket and eventually as a winding sheet (try doing that with just a pair of trousers :-) ). the "sort of a sash around their shoulers" is a remnant of the upper section of the belted plaid.

As for the 'Devils in Skirts' - I think it comes from (to paraphrase the late Kenneth Horne)'the sight of kilted Highlanders charging through the tall thistles, screaming'.

W