Just curious... As a strictly ornamental feature to kilt attire, is there any reason to remove and replace a sgian dubh (blade without sheath) frequently enough to be a problem? Unless you have a very nice one (maybe a damascus steel blade, or some sort of engraving) and enjoy sharing it with others? I understand that many are sold with a dull blade, making it useless for cutting anything.
I have no use for a knife that isn't sharp. An "ornamental" sgian dubh means it's part of a "costume". I don't wear my kilt as a costume, and my sgian dubh is sharp. I carry a pocket knife all the time when I'm wearing p@nts (and use it at least half a dozen times a day for various functions); since there isn't any way to carry it with a kilt, the sgian dubh fills its role. For me, it's a functional knife. It was sharp when I bought it and it will remain sharpened.

I disagree that the sgian dubh was historically an "ornamental" part of the attire, as historical Highlanders would likely have scoffed at such an idea; they being practical men. Modern Scots may use it only for ornamentation, but that doesn't mean that's the only role it must be relegated to.