The Sgian Dhu (pronounced "skee(a)n doo") is a Scottish blade; it is a short dagger with a black handle. The name is literally Scots Gaelic for "black knife." The weapon is only known to be used by Rakkety Tam MacBurl and his companion Wild Doogy Plumm.
Doogy and Tam temporarily lost their Sgian Dhus, and the rest of their weapons, when they disobeyed Squirrelking Araltum and his wife Idga Drayqueen; however, when the horde of Gulo the Savage killed many of Araltum's squirrels, the two warriors reclaimed their weapons and went after the wolverine.
Sgian Dhus appear in Rakkety Tam.