The skein dhu is a a dagger, carried in the hose top, by highlanders.
Now a days it is a ceremonial item , only worn with full dress uniform.
The Regimental Sgt Major, as the most senior NCO has a short sword with a unusual accoutrement in the outside of the sheath. In additon to the sword, he has a carving knife and a fork, that are fitted into the sheath, and they represent the tradition of the Clan Lord's "first man " having the honour to carve the joint of meat, at clan feasts.
At the Regimental " mess dinners " the RSM carves the joint of beef, and the meal is served to the Officers. The RSM is NOT a rank, it is an appointment, and he is called Mister, by all ranks, and Officers, alike. In action the RSM is the Colonel's personal body guard, and his task is to see that the Regiment is properly fed and resupplied, and to keep track of the wounded, and the dead, as to location and identification.
The RSM is the physcial embodiment of the Regiment and it's pride and traditions. He sets the tone for the men and the officers, if they are smart, listen well to his opinions.
Jim b. Toronto.